Brown meat with onion, drain. Add taco seasoning mix (follow directions on package for amount of water, etc) Pour 1/2 can of enchilada sauce in meat and simmer. Pour 1/2 can enchilada sauce in bottom of 13x9 baking dish. Spoon mixture into flour tortillas and add desired amount of cheese. Roll and place in baking dish. When all enchiladas are in pan, top with remaining can of enchilada sauce, and remaining cheddar cheese. Cover and bake at 350 for 45 minutes.