Beef Bulgogi stands as one of the most beloved dishes in Korean cuisine, captivating food lovers worldwide with its perfect balance of sweet and savory flavors. This iconic Korean BBQ dish features thinly sliced beef marinated in a mixture of soy sauce, sugar, sesame oil, garlic, and other seasonings, then quickly grilled to perfection.
The name “bulgogi” literally translates to “fire meat” in Korean, referring to the traditional cooking method of grilling the meat over an open flame. What makes this dish truly special is how the marinade tenderizes the beef while infusing it with layers of flavor that have been refined over generations.
Dating back to the Goguryeo era (37 BCE–668 CE), bulgogi has evolved from a simple royal court dish to a staple in Korean homes and restaurants across the globe. The beauty of beef bulgogi lies in its accessibility – while honoring traditional techniques, home cooks can easily recreate this dish with readily available ingredients.
Whether you’re new to Korean cooking or looking to perfect your bulgogi recipe, this guide will walk you through every step needed to create authentic beef bulgogi that rivals the best Korean restaurants. We’ll share time-tested techniques, explore the core ingredients that give bulgogi its distinctive taste, and offer helpful tips to ensure your Korean BBQ experience is nothing short of amazing.
From selecting the right cut of beef to achieving that perfect caramelization, this recipe combines traditional Korean cooking wisdom with practical home cooking methods. So prepare your taste buds for an unforgettable journey into Korean cuisine as we unlock the secrets to making truly outstanding beef bulgogi.
2. Key Benefits
Cooking beef bulgogi at home offers numerous advantages that go beyond just enjoying a delicious meal. Here’s why this Korean classic deserves a spot in your regular cooking rotation:
Nutritional Value
Beef bulgogi combines lean protein with a variety of nutrients essential for overall health. A typical serving provides:
- High-quality protein from beef, supporting muscle maintenance and growth
- Iron for healthy blood cell production and oxygen transport
- Zinc for immune system support and wound healing
- B vitamins, particularly B12, crucial for nerve function and energy production
- Antioxidants from garlic and onions that help combat inflammation
When prepared with lean cuts like sirloin or tenderloin, beef bulgogi can be a relatively low-fat option while still delivering satisfying flavor. The dish strikes an excellent balance between nutritional value and taste.
Quick Preparation
Despite its complex flavors, beef bulgogi is surprisingly easy to prepare:
- The marinade comes together in minutes using basic pantry ingredients
- Thin beef slices cook incredibly fast – often in just 2-3 minutes
- Prep work can be done ahead of time, making weeknight dinners stress-free
- The same marinade works well for meal prep, allowing you to plan multiple meals
This efficiency makes bulgogi an ideal option for busy home cooks who want to enjoy restaurant-quality meals without spending hours in the kitchen.
Versatility in Serving
Few dishes match beef bulgogi’s adaptability across different meal formats:
- Serve traditionally with rice and banchan (Korean side dishes)
- Use as filling for Korean-style tacos, sandwiches, or wraps
- Add to bibimbap bowls with vegetables and a fried egg
- Incorporate into fried rice for a flavor-packed one-dish meal
- Serve alongside noodles for a heartier option
This versatility ensures you’ll never grow tired of beef bulgogi, as it can transform into countless different meals.
Crowd-Pleasing Flavor Profile
The balanced sweet-savory taste of beef bulgogi appeals to a wide range of palates:
- The sweetness comes from natural ingredients like pear or apple
- Umami depth from soy sauce and beef creates a satisfying base
- Garlic and ginger add aromatic complexity without overwhelming heat
- The hint of sesame rounds out the flavor profile beautifully
Even those new to Korean cuisine typically enjoy beef bulgogi, making it an excellent gateway dish for exploring more Korean flavors.
Cost-Effective Gourmet Experience
Creating restaurant-quality bulgogi at home is surprisingly economical:
- Less expensive cuts like flank steak work wonderfully when properly sliced
- The marinade ingredients are affordable and versatile for other dishes
- One batch can stretch across multiple meals in different formats
- Making it at home costs a fraction of restaurant prices
For home cooks looking to maximize their food budget while still enjoying premium flavors, beef bulgogi offers exceptional value.

3. Ingredients
The magic of beef bulgogi lies in its perfect balance of simple yet flavorful ingredients. Each component plays a crucial role in creating that authentic Korean taste. Here’s everything you’ll need to prepare this classic dish at home:
For the Beef
1.5 pounds (680g) beef ribeye, sirloin, or tenderloin The foundation of excellent bulgogi starts with selecting the right cut of beef. While traditional bulgogi often uses ribeye for its perfect marbling and tenderness, sirloin and tenderloin make excellent alternatives. Look for cuts with some fat marbling for the most flavor.
Preparation tip: For easier slicing, freeze the beef for 30 minutes until it’s firm but not completely frozen. This helps achieve those signature paper-thin slices that cook quickly and absorb the marinade effectively.
For the Marinade
1/2 Asian pear (or sweet apple), peeled and grated This natural tenderizer contains enzymes that break down meat proteins, resulting in incredibly tender beef. The subtle sweetness also balances the savory elements in the marinade. If Asian pears aren’t available, sweet apples work well as substitutes.
5 tablespoons soy sauce Provides the foundational savory flavor and saltiness. Use regular soy sauce rather than light or dark varieties for authentic flavor.
3 tablespoons brown sugar Adds sweetness and helps create that lovely caramelization when the meat hits the hot pan. Brown sugar provides more depth than white sugar due to its molasses content.
2 tablespoons sesame oil Contributes a nutty aroma and flavor that’s instantly recognizable in Korean cuisine. Always use toasted sesame oil (darker in color) rather than light sesame oil for the best flavor.
4 cloves garlic, minced Garlic is essential in Korean cooking and adds aromatic depth to the marinade. Fresh garlic delivers significantly better results than pre-minced options.
1 tablespoon fresh ginger, grated Adds brightness and a subtle spicy note that balances the sweet and savory elements. Fresh ginger root is preferable to dried ginger powder for this recipe.
2 tablespoons green onions, finely chopped Provides mild onion flavor and fresh color. Use both the white and green parts for balanced flavor.
1 teaspoon black pepper Adds a gentle heat that complements the other flavors without overwhelming them.
2 teaspoons toasted sesame seeds Enhances the sesame flavor from the oil while adding pleasant texture and visual appeal.
For Cooking and Serving
1 medium onion, thinly sliced Often cooked alongside the beef, onions become sweet and flavorful as they absorb the marinade.
1 carrot, julienned (optional) Adds color, texture, and nutritional value. While not strictly traditional, carrots make a welcome addition to modern bulgogi preparations.
2 green onions, cut into 1-inch pieces Added during cooking for fresh flavor and color contrast.
1 tablespoon vegetable oil For cooking the beef if using a pan rather than a grill. Choose a neutral oil with a high smoke point.
Additional toasted sesame seeds and sliced green onions for garnish These finishing touches add visual appeal and reinforce the signature flavors.
Quality Considerations
For truly outstanding beef bulgogi, prioritize quality in these key ingredients:
- Beef: Choose well-marbled, fresh beef from a reputable butcher when possible
- Soy Sauce: A good-quality Korean or Japanese soy sauce makes a noticeable difference
- Sesame Oil: Look for pure, toasted sesame oil for the most authentic flavor
- Asian Pear: When in season, these make a significant difference in both flavor and tenderizing power
All these ingredients should be readily available at most grocery stores, though a trip to an Asian market will provide the most authentic options, particularly for items like Korean soy sauce and fresh Asian pears.

4. Instructions
Creating perfect beef bulgogi involves several key stages: preparing the beef, making the marinade, marinating, and cooking. Follow these step-by-step instructions for restaurant-quality results every time.
Preparing the Beef
- Partially freeze the beef (30 minutes in freezer) Place your beef in the freezer for about 30 minutes until it firms up but isn’t completely frozen. This crucial step makes it much easier to achieve the paper-thin slices essential for authentic bulgogi.
- Slice the beef against the grain Remove the beef from the freezer and place it on a cutting board. Using a sharp knife, slice the beef against the grain into pieces approximately 1/8-inch (3mm) thick. Slicing against the grain shortens the muscle fibers, resulting in more tender meat.
- Trim excess fat if desired While some fat adds flavor, you can trim larger pieces of fat from the edges if preferred. For a leaner dish, choose sirloin or tenderloin and trim more aggressively.
- Gently pound the slices (optional) For extra tenderness, you can lightly pound the slices with the flat side of a meat mallet or the back of a knife. This step is optional but helps tenderize tougher cuts.
Making the Marinade
- Prepare the Asian pear Peel half an Asian pear and grate it using a fine grater. The resulting puree will both flavor and tenderize the beef naturally.
- Combine wet ingredients In a large mixing bowl, combine the grated Asian pear, soy sauce, brown sugar, sesame oil,
- Add aromatics Add the minced garlic, grated ginger, chopped green onions, black pepper, and toasted sesame seeds to the bowl. Mix thoroughly to create a well-integrated marinade.
- Taste and adjust Before adding the beef, taste the marinade and adjust if needed:
- For more sweetness: add a teaspoon of brown sugar
- For more saltiness: add a teaspoon of soy sauce
- For more aromatic flavor: add more garlic or ginger
Marinating the Beef
- Combine beef and marinade Add the sliced beef to the marinade bowl and mix gently with clean hands or tongs, ensuring each slice is thoroughly coated. The thin slices should quickly absorb the flavors.
- Cover and refrigerate Transfer the beef and marinade to a sealable container or cover the bowl with plastic wrap. Place in the refrigerator to marinate:
- Minimum time: 1 hour
- Optimal time: 4 hours
- Maximum time: 24 hours (beyond this, the meat texture can begin to break down too much)
- Mix occasionally If possible, gently mix the beef once or twice during marination to ensure even flavor distribution.
Cooking the Beef
Option 1: Traditional Grilling Method
- Prepare your grill Heat a Korean BBQ grill, outdoor grill, or grill pan to medium-high heat (approximately 450°F/230°C). If using a charcoal grill, wait until the coals are covered with white ash.
- Grill the beef slices Working in batches to avoid overcrowding, place beef slices on the hot grill. Cook for approximately 1-2 minutes per side until the edges are caramelized and the beef is just cooked through.
- Add vegetables If using a tabletop grill, you can add sliced onions and green onions around the beef to cook simultaneously, absorbing the delicious beef flavors.
- Remove and rest Transfer cooked beef to a serving plate and let it rest for 2-3 minutes before serving.
Option 2: Stovetop Method
- Heat a large skillet or wok Place a large skillet or wok over medium-high heat and add 1 tablespoon of vegetable oil. Heat until the oil is shimmering but not smoking.
- Cook in batches Add beef slices in a single layer, being careful not to overcrowd the pan (overcrowding causes steaming rather than caramelization). Cook each batch for 2-3 minutes, stirring occasionally.
- Add vegetables When the beef is nearly done, add the sliced onions and green onions to the pan. Cook for an additional 1-2 minutes until the vegetables are slightly softened but still retain some crispness.
- Monitor liquid levels If too much liquid accumulates in the pan (from the marinade), increase the heat slightly to help it evaporate, concentrating the flavors.
Final Touches
- Garnish the dish Transfer the cooked bulgogi to a serving plate and sprinkle with additional toasted sesame seeds and sliced green onions.
- Rest briefly before serving Allow the beef to rest for 2-3 minutes before serving to let the juices redistribute throughout the meat.
- Serve immediately Beef bulgogi is best enjoyed hot off the grill or pan when the flavors are at their peak and the meat is at its most tender.
Storage and Reheating
If you have leftovers (which is rare!), store them in an airtight container in the refrigerator for up to 3 days. To reheat:
- Use a skillet over medium heat with a splash of water to prevent drying out
- Heat just until warmed through (about 2-3 minutes) to avoid overcooking
- Add a few drops of sesame oil at the end to refresh the flavors
Following these detailed instructions will help you create authentic beef bulgogi with the perfect balance of tender texture and rich flavor that makes this dish so beloved worldwide.

5. Pro Tips and Variations
After mastering the basic beef bulgogi recipe, consider these professional tips and creative variations to elevate your Korean BBQ experience even further. These insights come from experienced Korean cooks and culinary experts who have perfected bulgogi over years of practice.
Expert Tips for Perfect Bulgogi
Beef Selection and Preparation
Choose the right beef cut for your preference While ribeye offers the most traditional flavor due to its marbling, different cuts provide different experiences:
- Ribeye: Most flavorful with ideal fat content
- Sirloin: Leaner but still tender with good beef flavor
- Tenderloin: Most tender but less beefy flavor
- Flank or skirt steak: More chew but intense flavor (slice extra thin)
Freeze-slice-thaw method For the ultimate in thin slicing:
- Freeze beef completely (about 2 hours)
- Slice with a very sharp knife while still fully frozen
- Allow slices to thaw in the marinade This technique allows for incredibly thin, consistent slices that’s nearly impossible with fresh beef.
Ask your butcher for help Many butchers will slice the beef for bulgogi if asked. Request paper-thin slices cut against the grain, and explain it’s for Korean BBQ.
Marinade Mastery
Overnight marination sweet spot While 4 hours works well, many Korean home cooks swear by an overnight marinade (12-16 hours) for the perfect flavor penetration without breaking down the meat too much.
Double the aromatics, not the liquid To intensify flavor without making the marinade too salty or sweet, double the garlic, ginger, and green onions while keeping the soy sauce and sugar amounts the same.
Kiwi: The secret tenderizer Substitute half the Asian pear with 2 tablespoons of pureed kiwi for exceptional tenderness. Kiwi contains actinidin, an enzyme that tenderizes meat more effectively than the enzymes in pear. Be careful not to use too much or marinate too long, as it can make the meat mushy.
Marinade reserve technique Before adding the beef, set aside 2-3 tablespoons of marinade. Use this reserved portion to brush on the meat during cooking for an extra flavor boost and appealing glaze.
Cooking Perfection
The hot pan test To check if your pan is hot enough before adding the beef, sprinkle a few drops of water on the surface. If they sizzle and evaporate immediately,
6. Serving Suggestions
The beauty of beef bulgogi lies not only in its delicious flavor but also in its versatility when it comes to serving. From traditional Korean presentations to modern fusion options, here are the best ways to enjoy your homemade bulgogi.
Traditional Korean Service
Ssam Style (Lettuce Wraps)
One of the most popular and interactive ways to enjoy beef bulgogi in Korea is as part of ssam:
- Arrange a platter with fresh, crisp lettuce leaves (romaine, green leaf, or butter lettuce work well)
- Place small bowls of accompaniments around the table:
- Ssamjang (a thick, spicy paste made from doenjang and gochujang)
- Thinly sliced raw garlic
- Sliced green chilies
- Additional toasted sesame seeds
- To eat, place a lettuce leaf in your palm, add a spoonful of rice, top with bulgogi and desired accompaniments, then fold into a small wrap
- Eat in one or two bites for the perfect combination of flavors and textures
This hands-on dining style creates a communal, festive atmosphere perfect for gathering with family and friends.
Rice Bowl (Bulgogi Deopbap)
The simplest yet most satisfying way to enjoy bulgogi is over a bowl of freshly steamed rice:
- Place a generous serving of hot white rice in a bowl
- Top with bulgogi, including some of the cooking juices for added flavor
- Garnish with sliced green onions and toasted sesame seeds
- Serve with kimchi and other banchan (side dishes) on the side
This everyday approach allows the bulgogi to shine while the rice soaks up all the delicious sauce.
Banchan Spread
For an authentic Korean table setting, serve bulgogi as the main protein alongside numerous small side dishes:
Essential banchan to include:
- Kimchi (cabbage or radish)
- Namul (seasoned vegetables like spinach, bean sprouts, or bracken fern)
- Gamja jorim (braised potatoes)
- Kongnamul (seasoned soybean sprouts)
- Pickled radish
- Gyeran mari (rolled omelet)
The variety of flavors, textures, and colors creates a balanced meal representative of traditional Korean dining philosophy.
Modern Serving Ideas

Bulgogi Tacos
Fusion food at its finest, bulgogi tacos combine Korean and Mexican flavors to delicious effect:
- Warm corn or flour tortillas
- Fill with beef bulgogi
- Top with:
- Quick pickled vegetables (carrots and radish work well)
- Cilantro
- Thinly sliced avocado
- Gochujang crema (mix sour cream with a small amount of gochujang)
- Serve with lime wedges for squeezing over the top
The combination of spicy, sweet, tangy, and fresh flavors makes these tacos irresistible.
Bulgogi Loaded Fries
For an indulgent treat that’s perfect for game day or casual gatherings:
- Prepare crispy french fries or sweet potato fries
- Top with beef bulgogi and its cooking juices
- Add toppings:
- Shredded cheese (mozzarella or monterey jack work well)
- Sliced green onions
- Sesame seeds
- Kimchi (optional)
- Sriracha or gochujang mayo drizzle
- Serve immediately while hot
This crowd-pleasing dish combines the comfort of loaded fries with the bold flavors of Korean BBQ.
Bulgogi Bibimbap
Create this rice bowl dish featuring bulgogi as the star protein:
- Place warm rice in a bowl
- Arrange small portions of various vegetables around the edge:
- Julienned carrots
- Sautéed spinach
- Bean sprouts
- Sliced cucumber
- Sliced mushrooms
- Add beef bulgogi in the center
- Top with a fried egg
- Serve with gochujang sauce on the side
Bibimbap literally means “mixed rice,” so before eating, add gochujang to taste and mix everything together thoroughly.
Complementary Beverages
To complete your beef bulgogi meal, consider these traditional and contemporary beverage pairings:
Traditional Korean options:
- Soju: Korea’s clear, neutral spirit, similar to vodka but typically lower in alcohol
- Sikhye: A sweet rice drink often served as dessert
- Barley tea (boricha): A roasted barley tea served hot or cold
Contemporary pairings:
- Asian lagers (Hite, OB, Asahi)
- Craft IPAs with citrus notes
- Yuzu-based cocktails or mocktails
Non-alcoholic choices:
- Cold barley tea
- Roasted corn tea
- Plum tea (maesil cha)
- Sparkling water with a splash of citrus
Presentation Tips
The visual appeal of your bulgogi serving can enhance the dining experience:
- Choose appropriate serving dishes
- For traditional service: stone bowls (dolsot) or cast-iron plates retain heat
- For modern presentation: white plates provide contrast to showcase the vibrant colors
- Color contrast
- Add garnishes like green onions, toasted sesame seeds, or julienned carrots
- Include bright banchan like kimchi or yellow pickled radish
- Sizzle factor
- If possible, serve bulgogi on a hot plate that continues cooking and sizzling at the table
- The aroma and sound add to the sensory experience
- Family style
- Place a large platter of bulgogi in the center of the table for sharing
- Surround with smaller dishes of banchan and rice
Whether you opt for a traditional Korean table setting or a modern fusion approach, beef bulgogi’s adaptability ensures it will be the centerpiece of a memorable meal that brings people together around the table.
7. Conclusion
Beef bulgogi represents more than just a popular Korean dish—it embodies the heart of Korean culinary tradition while offering remarkable accessibility to home cooks worldwide. This perfect harmony of sweet, savory, and umami flavors has rightfully earned its place as one of the most beloved dishes to emerge from Korean cuisine.
Throughout this guide, we’ve explored the essential elements that make beef bulgogi special. From selecting the right cut of beef and slicing it properly to creating that perfect balance of flavors in the marinade, each step contributes to the distinctive character of this timeless dish. The versatility of bulgogi—whether served traditionally with rice and banchan or reimagined in fusion creations—speaks to its enduring appeal across different culinary contexts.
What makes beef bulgogi particularly valuable for home cooks is its combination of impressive flavor and straightforward preparation. Unlike many restaurant-quality dishes that require specialized equipment or hard-to-find ingredients, bulgogi delivers restaurant-worthy results with standard kitchen tools and readily available components. The marinade does most of the heavy lifting, transforming simple ingredients into something truly special.
The communal nature of bulgogi also deserves recognition. Traditionally enjoyed as part of a shared meal, it brings people together around the table—whether sizzling on a tabletop grill or served family-style in a large dish. This social aspect reflects the Korean value of togetherness during meals, making bulgogi not just delicious food but an experience to be shared.
For those new to Korean cooking, beef bulgogi serves as an ideal introduction—approachable in technique while delivering authentic flavors. As you gain confidence with this recipe, you might explore other Korean classics like bibimbap, japchae, or various banchan to complement your bulgogi skills.
Remember that cooking is ultimately about making food that brings joy, and beef bulgogi excels in this regard. Don’t hesitate to adapt the recipe to your personal preferences—perhaps adjusting the sweetness, trying different cuts of beef, or incorporating additional vegetables. The core techniques and flavor principles will guide you toward delicious results, even as you make the recipe your own.
Whether you’re preparing a special dinner for family, hosting friends for a Korean-inspired feast, or simply treating yourself to something delicious after a long day, beef bulgogi delivers satisfaction with every bite. Its perfect balance of flavors, its connection to rich culinary tradition, and its adaptability for modern kitchens make it a recipe worth mastering.
So heat up your grill or skillet, gather your ingredients, and prepare to experience the magic of beef bulgogi in your own kitchen. With the techniques and insights shared in this guide, you’re well-equipped to create a meal that will impress even the most discerning palates—including your own.
8. FAQs
What is the best cut of beef to use for bulgogi?
The traditional choice for beef bulgogi is ribeye, which offers excellent marbling and flavor. However, sirloin and tenderloin are excellent alternatives that provide a good balance of tenderness and taste. For a more budget-friendly option, flank or skirt steak work well when sliced very thinly against the grain. The key is to choose a cut that has some fat content for flavor, but not so much that the dish becomes greasy.
Can I make beef bulgogi without an Asian pear?
Absolutely! While Asian pear is traditional and provides both natural sweetness and meat-tenderizing enzymes, there are several effective substitutes:
- Sweet apple (such as Fuji or Gala)
- Kiwi fruit (use less, as it’s a more powerful tenderizer)
- Canned pineapple (about 2 tablespoons)
- Even 2 tablespoons of regular apple juice plus 1 teaspoon of sugar
Each alternative will slightly alter the flavor profile but will still result in delicious bulgogi with good tenderness.
How can I make beef bulgogi if I don’t have a grill?
A grill gives bulgogi its characteristic char and smoky flavor, but a heavy skillet or wok on the stovetop produces excellent results. Heat your pan until very hot, add a small amount of oil, and cook the marinated beef in small batches to avoid overcrowding. The key is to maintain high heat so the meat sears rather than steams. For the closest approximation to grilled flavor, a cast-iron skillet works best due to its excellent heat retention.
Is beef bulgogi spicy?
Traditional beef bulgogi is not spicy. It features a balanced sweet-savory flavor profile with garlic and ginger providing aromatic qualities rather than heat. However, many Korean restaurants and home cooks serve spicy condiments alongside bulgogi, such as gochujang (Korean chili paste) or sliced fresh chilies, allowing diners to add heat according to their preference. If you prefer a spicier version, you can add 1-2 tablespoons of gochujang to the marinade.
How far in advance can I marinate the beef?
The beef can be marinated for as little as 30 minutes in a pinch, but the ideal marination time is between 4 and 24 hours. Beyond 24 hours, the meat can begin to break down too much due to the acidic and enzymatic components in the marinade, potentially resulting in mushy texture. For best results, aim for overnight marination (12-16 hours), which allows the flavors to fully penetrate while maintaining proper texture.
Can beef bulgogi be made ahead of time?
Yes, beef bulgogi can be prepared in advance in several ways:
- Marinate the beef up to 24 hours ahead and cook just before serving
- Cook the bulgogi completely, refrigerate for up to 3 days, and gently reheat
- Freeze cooked bulgogi for up to 2 months in airtight containers
For the best flavor when reheating, use a skillet rather than a microwave, add a small splash of water to prevent drying, and finish with a few drops of sesame oil to refresh the flavor
Is beef bulgogi gluten-free?
Traditional beef bulgogi recipes are not gluten-free due to the soy sauce, which contains wheat. However, it’s easy to make a gluten-free version by substituting tamari (gluten-free soy sauce) or coconut aminos for regular soy sauce. Always check labels to ensure your chosen substitute is certified gluten-free. The other ingredients in typical bulgogi recipes are naturally gluten-free.
What vegetables go well with beef bulgogi?
While onions and green onions are the most common vegetables cooked with bulgogi, many others pair wonderfully with the dish:
- Bell peppers (any color)
- Mushrooms (especially shiitake or button)
- Carrots (julienned)
- Zucchini (sliced thinly)
- Spinach (added at the very end of cooking)
For a colorful and nutritious meal, you can create a “bulgogi stir-fry” by cooking your choice of vegetables alongside or shortly after the beef.
Why is my beef bulgogi tough?
Several factors can contribute to tough beef bulgogi:
- The beef wasn’t sliced thinly enough
- The beef wasn’t sliced against the grain
- Insufficient marination time
- Overcooking the beef
- Using a cut with too little fat or too much connective tissue
For tender bulgogi, ensure you’re slicing the beef very thinly (partial freezing helps), always cut against the grain, marinate for at least 4 hours, and cook quickly over high heat just until the meat is no longer pink.