Heat olive oil in a large skillet over medium heat. Add diced onion and bell peppers. Sauté for about 5 minutes until vegetables are soft and fragrant.
Add ground beef to the skillet. Break it up with a spoon and cook until browned.
Add spices—garlic powder, chili powder, cumin—and continue to cook, stirring well.
In a separate pan, fry cauliflower rice until tender, about 5 minutes.
Assemble bowls: layer cauliflower rice, top with beef mixture, and garnish with tomatoes, cilantro, and lime.
Notes
Refrigerate leftovers in an airtight container for up to 3 days. Reheat in microwave or skillet.