In large skillet, heat canola oil over medium heat. Add red onion and red bell pepper; cook 8 minutes. Add black beans and red pepper flakes; cook 3 minutes. Season with salt and pepper, to taste. Transfer to dish.
In medium bowl, whisk eggs and egg whites. Stir in cheese until combined. Heat large skillet over low heat, add egg mixture and scramble 3 minutes, or until cooked through.
Spread sour cream over tortilla. Spread salsa over sour cream. Spoon 1/4 bean mixture over salsa. Spoon 1/4 scrambled eggs over bean mixture. Top with diced tomatoes and avocado. Drizzle with hot sauce, if desired. Roll-up burrito. Repeat three times with remaining ingredients and serve.