Brush the foil with some of the melted margarine. Place a piece of cod in the center of each piece of foil and brush with the remaining margarine.
In a small bowl combine the Dijon mustard, capers, parsley, lemon juice, and Tabasco and mix well. Spread the mixture evenly on the fish and sprinkle with pepper. Loosely enclose the fish in the foil and grill for 8 to 10 minutes. Do not overcook the cod.