Heat a nonstick skillet over medium heat. Add the ground beef and onions. Cook, breaking it up, until browned and cooked through. Drain excess fat if needed.
Add the garlic and ginger. Sauté for 2 minutes until fragrant and softened.
Toss in the sliced cabbage and stir well. Cook for 7 minutes, stirring frequently, until the cabbage is tender but still crisp.
Add the soy sauce, sesame oil, and rice vinegar. Toss everything together and adjust the salt/pepper if needed.
Garnish with green onions and sesame seeds if using.