* Flour Tortillas should be 7 to 20 cm in diameter and cut into strips. Heat the margarine and oil in a 25 cm skillet over medium heat until hot. Add the tortilla strips and onion; cook, stirring occasionally, until the tortillas are brown. Mix the remaining ingredients except the cheese and pour into the skillet. As the mixture begins to set at the bottom and sides, gently lift the cooked portion so that the uncooked eggs can run under the cooked portion. Avoid constant stirring. Turn the egg mixture, cook until the eggs are all cooked through but still moist, 3 to 5 minutes. Sprinkle with the cheese and serve.