In a large skillet, heat the olive oil over medium heat. Add the diced onion and cook until softened, about 3-4 minutes.
Add the ground beef to the skillet, breaking it apart with a spatula. Cook until browned and no longer pink, about 5-7 minutes. Drain excess fat if necessary.
Stir in the diced red and green bell peppers and minced garlic. Cook for an additional 3-4 minutes until the peppers are tender.
Season the mixture with cumin, smoked paprika, salt, and black pepper. Stir well to combine.
Add the cooked rice to the skillet, followed by the soy sauce and sesame oil. Mix everything together until heated through, about 2-3 minutes.
Serve the beef and pepper mixture in bowls, garnished with sliced green onions and sesame seeds if desired.