1.) Spray a large skillet with cooking spray and place over medium heat. Cook the peppers and onion, stirring occasionally, until soft, about 5 minutes. Transfer the mixture to a bowl.
2.) Whisk the eggs in a seperate medium bowl. Spray the skillet again with cooking spray. Scramble in the skillet over medium heat until fully cooked. Stir in the peppers and onion mixture and cheese, and season with salt and pepper to taste. Remove from the heat.
3.) Spread each whole-wheat tortilla with 1 tablespoon of sour cream down the center and top with one-quarter of the avocado slices. Place one-quarter of the egg mixture on each tortilla, fold over the side edges, and roll into a burrito. Top each with 1 tablespoon of salsa.