1. Make the sauce: in a bowl mix brown sugar, soy sauce, sesame oil, black pepper and red chili flakes. set aside.
2. In a large skillet heat vegetable oil over medium heat. Add ginger and garlic, cook for 1 minute. Increase to high heat, add the ground beef and cook, breaking it into crumbles, until no longer pink, about 5-7 minutes. Drain excess grease.
3. Pour the sauce over the ground beef, add 1/2 of the chopped green onions and let simmer, stirring occasionally, for 2-3 minutes.
4. serve with hot rice and garnish with green onions and toasted sesame seeds.