Combine ground sirloin with first four ingredients in pan, cooking over medium heat. Drain any fat.
Add tomatoes, 2/3 of the can of enchilada sauce, and salt and pepper to taste.
Bring to boil; reduce heat and simmer for 10 minutes.
Meanwhile, combine both cheeses and egg white in food processor until blended and American cheese is in pieces; set aside.
In frying pan coated with no stick cooking spray, heat remaining enchilada sauce a little at a time and fry flour tortillas until soft.
Remove, continuing to add sauce and fry tortillas until all have been done.
Spoon one-third meat mixture into a 12x8x2-inch baking dish.
Spoon half cheese mixture over meat.
Top with half of tortillas. repeat layers ending with meat.
Bake at 350° F for 25 minutes. Let stand for 5 minutes before cutting.
Servings: 8