Heat oil in a large skillet or wok over medium-high heat.
Add ground beef and cook until browned, breaking it apart with a spatula.
Stir in garlic and ginger, cooking until fragrant.
Add bell pepper, broccoli, and carrots, cooking for 3-5 minutes until slightly tender.
In a small bowl, mix soy sauce, oyster sauce, sesame oil, and red pepper flakes.
Pour sauce over stir-fry and toss to combine.
Cook for another 2 minutes, then remove from heat and sprinkle with green onions.
Serve hot over cooked rice.