In a large skillet, heat the olive oil over medium heat. Add the diced onion and cook for about 3-4 minutes until softened.
Add the minced garlic and diced bell pepper to the skillet, cooking for an additional 2-3 minutes until the peppers are tender.
Stir in the ground turkey and cook until browned and cooked through, about 6-8 minutes.
Add the black beans, corn, and taco seasoning to the skillet. Mix well and cook for another 5 minutes, allowing the flavors to meld.
To assemble the taco bowls, divide the cooked brown rice or quinoa among four bowls. Top each bowl with the turkey mixture, cherry tomatoes, avocado, shredded lettuce, and cheese.
Garnish with fresh cilantro and serve with lime wedges on the side for squeezing over the top.