Start by making rice according to package instructions. Note, cooking times will change depending on the type of rice. While rice cooks, prepare everything else.
Seed and thinly slice the red bell peppers. In a pan heat oil over medium heat and add the bell pepper. Saute for about 10 minutes, until they become tender and slightly wilted. Add the spices (cumin, chili flakes, garlic powder, paprika and salt) and the black beans and mix together. Continue to cook for another 5 minutes, stirring often, unti the beans are heated all the way through. Remove from heat stir in the cilantro. Taste and adjust seasonings.
To make the gucamole, slice the avocados in half, remove the pit, and scoop the avocado into a large bowl. Mash the avocado so that only a few small pieces remain. Add the remaining gucamole ingredients (tomatoes, onions, lime juice and salt) and mix together. Taste and adjust lime juice and salt if needed.
To assemble the burritos, place tortillas on a flat surface and spoon about ½ cup of rice in the center of the tortilla. Top with about ⅓ cup of black beans, a scoop of guacamole, and chopped lettuce. Fold the top and bottom over the filling and roll up or wrap tightly in foil and cut in half. Serve immediately.