Saute an onion in butter or oil. Add chopped leftover turkey and cook until reheated. Grate your favorite cheese. Open a can or bottle of your favorite enchilada sauce. Warm a stack of small corn tortillas. In each tortilla, place a tablespoon of turkey and onion filling and a bit of cheese. Roll. Place in an 8- by 8- or 9- by 9- inch baking pan. Repeat until pan is full. Cover with enchilada sauce and then cheese. Cook at 350 degrees until cheese is melted and golden.