In a small bowl, mix together the cumin, chili powder, garlic powder, salt, and pepper. Rub the mixture all over the chicken breasts.
Heat the olive oil in a large skillet over medium-high heat. Add the chicken breasts and cook for 6-8 minutes per side, or until cooked through. Remove the chicken from the skillet and set aside to cool.
In the same skillet, add the diced bell pepper and onion. Cook until softened, about 5 minutes.
While the vegetables are cooking, shred the chicken using two forks or your hands.
Add the shredded chicken to the skillet with the vegetables and stir to combine.
Add the cooked rice and black beans to the skillet and stir until everything is well combined.Warm the flour tortillas in the microwave or on a dry skillet, for about 20-30 seconds.
To assemble the burritos, lay a tortilla on a flat surface. Spoon some of the chicken mixture onto the center of the tortilla, leaving a little room around the edges. Sprinkle some shredded cheese on top. Roll the tortilla up tightly, tucking in the edges as you go, to create a burrito.
Heat a clean skillet over medium heat and place the burritos on the skillet, seam-side down. Cook for 1-2 minutes per side, or until lightly golden and crispy.
Serve the burritos with lettuce, salsa, sour cream, and cilantro, if desired.
Notes
Feel free to adjust the spices and ingredients to your taste preference. You can also add additional toppings such as lettuce, avocado or jalapenos.