Place soup and onion in blender on puree until smooth. Combine 1 cup of soup mixture with chicken. Spoon enough meat mixture and cheese on each tortilla to cover 1/3 of tortilla, reserving 1 cup of cheese for the top. Roll up each tortilla beginning with the filled edge. Place seam side down in greased 13x9 inch baking dish. When tortillas are completed, cover with the sauce made by combining the soup, sour cream and chilies and freeze with the extra cheese in a bag taped to the baking dish.
When thawed, sprinkle remaining cheese on top and bake, uncovered, at 375 degrees for 20 to 25 minutes. Serves 8 to 10