In a large skillet over medium heat, brown the ground beef until fully cooked. Drain any excess fat.
Add the diced onion and garlic to the beef. Cook for 2-3 minutes until fragrant and soft.
Stir in the shredded cabbage and sauté until slightly wilted, about 5 minutes.
Add soy sauce, sesame oil, rice vinegar, ground ginger, red pepper flakes, salt, and pepper. Mix well and cook another 2-3 minutes until cabbage is tender.
Garnish with sliced green onions and sesame seeds before serving.
