Drain 1 can tuna. In frying pan, melt 1 1/2 Tbs marg. Add 1 Tbs flour & quickly stir; then add enough milk for a creamy sauce. Do not use high heat, because it will stiffen too fast. Add drained tuna & stir until hot, adding more milk if necessary. Salt & pepper to taste. (Note: If marg & flour form a lumpy mess, before adding milk, start over; it's easier to start over at this point than when you add milk & have a more lumpy mess.)