In a large skillet over medium heat, cook the ground beef or turkey until browned, breaking it apart with a spatula. Drain any excess fat if necessary.
Stir in the taco seasoning, adding a splash of water if needed. Cook for an additional 2-3 minutes until the meat is well-coated and heated through. Season with salt and pepper to taste.
In a separate pot, heat the black beans and corn over medium heat until warmed through.
To assemble the bowls, start with a base of rice in each bowl. Top with the seasoned meat, black beans, corn, diced tomatoes, shredded lettuce, and cheddar cheese.
Add diced avocado and a dollop of sour cream on top of each bowl. Garnish with chopped cilantro and serve with lime wedges on the side.