Heat olive oil in a large non-stick skillet over medium heat.
Add diced onion and cook for 3-4 minutes until softened.
Add minced garlic and cook for 1 minute until fragrant.
Add ground beef to the skillet, breaking it apart with a spatula. Cook until browned and no longer pink, about 6-8 minutes.
Drain any excess fat from the skillet if necessary.
Add diced red bell pepper and zucchini to the skillet. Cook for 5 minutes until vegetables are tender.
Stir in canned diced tomatoes, ground cumin, smoked paprika, chili powder, black pepper, and salt. Simmer for 5 minutes to blend flavors.
While the beef mixture simmers, heat a separate non-stick skillet over medium heat.
Add cauliflower rice and cook, stirring frequently, for 5 minutes until tender but not mushy.
Divide cauliflower rice evenly among four plates.
Top each plate of cauliflower rice with the ground beef and vegetable mixture.
Garnish each serving with chopped fresh cilantro and serve immediately.