Heat olive oil in a large skillet over medium heat and sauté the diced bell pepper for 4-5 minutes until softened.
Add the black beans, corn, cumin, and chili powder to the skillet, stirring to combine, and cook for 3-4 minutes until heated through.
Warm the tortillas in the microwave for 20-30 seconds or in a dry skillet to make them more pliable.
Lay one tortilla flat and layer with about 1/3 cup rice, 1/3 cup bean mixture, 2-3 tablespoons cheese, and 2 tablespoons salsa down the center.
Fold in the sides of the tortilla, then roll from the bottom up tightly to form a burrito.
Repeat with remaining tortillas and fillings, then serve immediately with sour cream and additional toppings as desired.