Brown ground beef and onions seasoned with salt and pepper and drain.
Put 1/2 can of enchilada sauce in the bottom of a 13 X 9 baking dish.
Mix the other half of enchilada sauce with ground beef mixture and add 1 1/2 cups shredded Mexican cheese.
Place small amount of ground beef mixture in each tortilla shell and roll up. Place each one in the baking dish
Top with 1 can red enchilada sauce and the remaining cheese.
Bake uncovered at 350 for 20 minutes. Garnish with diced tomatoes, lettuce and sour cream