Preheat oven to 425°F (220°C). Toss cauliflower with 1 tbsp olive oil, salt, and pepper. Spread on baking sheet in single layer.
Roast 20-25 minutes, stirring halfway through, until golden and crispy at edges.
While cauliflower roasts, heat 1 tbsp olive oil in skillet over medium-high. Sauté onion 3-4 minutes until translucent. Add garlic and cook 30 seconds.
Add ground beef, breaking apart with spoon. Cook 6-8 minutes until browned completely.
Stir in chile powder, paprika, cumin, cayenne (if using), salt and pepper. Cook 2 minutes, stirring constantly.
Remove from heat. Stir in lime juice and cilantro.
Divide roasted cauliflower among bowls. Top with ground beef.
Add desired toppings and serve immediately.
Notes
Use 85% lean beef for best balance of flavor and health.
Cut cauliflower evenly for uniform cooking.
Store beef and cauliflower separately for best texture.