In a large skillet over medium-high heat, add the ground beef. Cook until browned, breaking it apart with a spatula, about 5-7 minutes. Drain any excess fat if necessary.

In a bowl, whisk together the soy sauce, brown sugar, sesame oil, minced garlic, minced ginger, rice vinegar, gochujang, and black pepper until well combined.

Pour the sauce over the cooked ground beef in the skillet. Stir to coat the beef evenly with the sauce.

Reduce the heat to medium and let it simmer for about 5 minutes, allowing the flavors to meld together.

Stir in the sliced green onions and cook for an additional minute.

Serve the bulgogi over cooked rice and sprinkle with sesame seeds if desired.