In a large skillet over medium heat, melt the butter.
Add diced onion, green bell pepper, red bell pepper, and jalapeño. Cook for about 5 minutes, until slightly softened.
Add the ground beef and cook, breaking it apart with a spatula, until fully browned and the vegetables are tender.
Drain any excess fat from the skillet, then return the beef mixture to the heat.
Stir in the soy sauce, garlic powder, salt, and black pepper. Mix thoroughly and cook for another 2–3 minutes to combine flavors.
Spoon the beef and pepper mixture over bowls of warm cooked rice. Serve immediately and enjoy!