Brown the ground beef in a skillet over medium heat. Stir frequently until cooked through, and season with chili powder, salt, and pepper to taste. Drain excess fat and set aside.
In the same skillet, add the cauliflower rice and cook for about 5 minutes until tender. Add a touch of lime juice for brightness.
While the rice cooks, chop the tomatoes, slice bell pepper, and dice the avocados. Prepare your toppings ready for assembling.
In serving bowls, layer cauliflower rice as the base, followed by the ground beef, black beans, and bell peppers.
Garnish with shredded lettuce, tomatoes, avocado slices, cheddar cheese, and a dollop of sour cream. Serve with a lime wedge.
Notes
Store assembled bowls without fresh avocado. Add the avocado slices just before serving for freshness.