Brown the beef in a skillet over medium-high heat until no pink remains, about 5 minutes, then drain most of the fat.

Whisk together soy sauce, brown sugar, sesame oil, garlic, ginger, gochujang, and rice vinegar until the sugar dissolves.

Reduce heat to medium, pour the sauce over the beef, and stir for 2 to 3 minutes until the liquid thickens and coats the meat. Serve over rice with green onions and sesame seeds.