1.Place bell pepper in the oven and broil for a few minutes on each side to blacken skin. Place in a small paper bag and fold over the top; let stand for 5 minutes.
2.Rub off skin from the peppers. Cut open, remove seeds, and chop.
3.Spray a medium skillet with nonstick cooking spray.
4.Add onions and cook over medium heat for 10 minutes or until very soft.
5.Stir in bell pepper and nopales and cook for 5 minutes more.
6.Add tomato and chili powder and remove from heat.
7.In a medium bowl, beat egg whites, whole eggs, and salt. Add to skillet; stir and cook for 5 minutes or until eggs are cooked through.
8.Top with cheese and salsa. Serve immediately with warm tortillas.