Heat a large skillet over medium heat. Once hot, add the lean ground beef, using a spatula to break it into smaller pieces. Cook for about 5–7 minutes until browned and fully cooked.

Stir in the finely diced onion and minced garlic to the skillet with the cooked beef. Sauté for 2–3 minutes until the onion becomes translucent and fragrant.

Add shredded cabbage to the skillet, mixing it throughout. Cook for about 5 minutes until the cabbage starts to wilt and soften slightly.

Pour in soy sauce, sesame oil, rice vinegar, ground ginger, and red pepper flakes. Stir everything together and let it cook for another 2–3 minutes.

Once combined and heated through, remove from heat. Serve hot, garnished with sliced green onions and toasted sesame seeds.