Heat a large skillet over medium heat and add ground beef, breaking it up as it cooks for 6-8 minutes until browned and no pink remains.
Drain excess grease, then add sesame oil and toss to coat.
Add garlic and sauté for 30-60 seconds until fragrant.
Stir in soy sauce, brown sugar, fish sauce, ginger, and crushed red pepper until sugar dissolves.
Simmer for 3-5 minutes, stirring occasionally, until sauce thickens and coats the beef with a glossy finish.
Remove from heat and garnish with chopped green onions.
Serve over rice or noodles.