In a medium bowl, whisk together the olive oil, chili powder, ground cumin, smoked paprika, salt, and freshly ground black pepper. Add the chicken breasts, ensuring they are well coated in the marinade. Cover and let them marinate for at least 20 minutes, or refrigerate for up to 2 hours for deeper flavor.
Preheat a grill or stovetop skillet over medium heat. Once hot, add the marinated chicken breasts. Cook for approximately 6-7 minutes on each side, or until they are fully cooked through and no longer pink in the center, reaching an internal temperature of 165°F (75°C). After cooking, remove the chicken from the heat and allow it to rest for 5 minutes before slicing into strips.
While the chicken is cooking, prepare the base of your burrito bowl. In a large mixing bowl, combine the cooked quinoa or brown rice, black beans, sweet corn, finely diced red bell pepper, and halved cherry tomatoes. Gently toss the mixture together, and season with salt and pepper to taste.
Divide the quinoa or rice mixture among four serving bowls. Arrange the sliced grilled chicken on top, followed by a generous portion of sliced avocado and, if desired, a sprinkle of shredded cheddar cheese.
Finish off the bowls by generously scattering chopped fresh cilantro over each serving. Offer lime wedges and your choice of salsa or hot sauce on the side for an extra burst of flavor.
Notes
For a vibrant display, layer the ingredients in each bowl in a rainbow fashion.