Heat the margarine in a frying pan and quickly saute the tortilla (about a minute on each side). Place the tortilla on a piece of waxed paper. Spread the taco sauce on the tortilla. Sprinkle the chicken, cheese, and lettuce on one third of the tortilla. Then roll the tortilla up, starting with the side where the chicken mixture is and folding the ends in to prevent the mixture from dripping out. Wrap the waxed paper around the taco and pack it in a plastic bag. Makes 1 taco.