In a large skillet, heat the olive oil over medium heat. Add the diced onion and minced garlic, sautéing until the onion is translucent, about 3-4 minutes.

Add the ground beef to the skillet, breaking it apart with a spatula. Cook until browned, about 5-7 minutes. Drain excess fat if necessary.

Stir in the diced bell peppers, soy sauce, black pepper, paprika, salt, and crushed red pepper flakes (if using). Cook for an additional 5 minutes, until the peppers are tender.

Serve the beef and pepper mixture over a bed of cooked rice. Garnish with sliced green onions.