Heat sesame oil in a pan over medium heat.
Add chopped onion and minced garlic; cook until fragrant.
Stir in the ground beef, breaking it apart as it browns.
Mix in soy sauce, brown sugar, and grated ginger.
Add chili flakes if you want a little kick.
Cook for another few minutes until the sauce thickens slightly.
Serve over hot rice and top with green onions and sesame seeds.