Heat a large skillet over medium-high heat. Add beef and cook, stirring and crumbling into small pieces until browned, 5 to 7 minutes. Drain excess grease.
Add garlic, ginger, and sesame oil, stirring until fragrant, about 2 minutes. Stir in soy sauce, brown sugar, and red pepper. Cook until some of the sauce absorbs into the beef, about 7 minutes. Add 1/2 of the chopped green onions.
Serve beef over hot cooked rice; garnished with sesame seeds and remaining green onions.
