In a mixing bowl, combine ground beef or bulgogi beef with soy sauce, brown sugar, minced garlic, grated ginger, and sesame oil. Mix thoroughly until the beef is well coated with the marinade. Cover the bowl with plastic wrap and refrigerate for at least 1 hour to infuse the flavors; for the best results, marinate overnight.

After marinating, remove the beef from the refrigerator. Divide the mixture into four equal portions and shape each portion into a patty about ¾ inch thick. Use your thumb to make a small indent in the center of each patty to prevent them from puffing up during cooking.

Heat your grill to medium-high, approximately 400°F (200°C). Ensure the grates are clean and oiled to prevent sticking. Wait for about 10 minutes until the grill is hot.

Carefully place the patties on the grill and cook for 4-5 minutes on one side without moving them. Flip the patties and grill for another 3-4 minutes until they reach an internal temperature of 160°F (71°C) for medium doneness.

While the patties are grilling, split your burger buns in half and lightly butter them. Place them cut-side down on the grill for about 1-2 minutes until golden brown and toasted.

Once the patties and buns are ready, it’s time to assemble your Bulgogi Kimchi Burger! Start by placing a patty on the bottom half of each toasted bun. Top it generously with kimchi, followed by fresh lettuce and tomato slices. Add cheese if you desire, and then cap with the top bun.

Serve the assembled Bulgogi Kimchi Burgers immediately while they are hot. Pair them with crispy sweet potato fries or a refreshing side salad for a complete meal.