In a small saucepan cook green peppercorns in 1 tablespoon hot margarine or butter for 1 minute. Stir in the flour and dash salt. Stir in the 3/4 cup half-and-half, light cream, or milk all at once. Cook and stir over medium heat until thickened and bubbly. Remove half of the peppercorn mixture from the pan. Cover with plastic wrap and set aside. Stir salmon or tuna into remaining mixture in saucepan. Set aside.
Unfold phyllo dough. Brush 1 sheet of phyllo dough with some of the 3 tablespoons melted margarine or butter. Top with a second sheet of phyllo, then brush with more margarine. Repeat layering with remaining phyllo sheets and margarine (reserve some of the margarine). Cut the phyllo stack lengthwise in half.
To assemble, spread half of the salmon mixture along one short side of each phyllo strip to within 1 inch of the long sides. Fold the short end of phyllo over the salmon mixture and roll up, folding in the sides as you roll. Brush the seam with margarine; press to seal. Place rolls, seam side down, in a shallow baking dish. Cut diagonal slits about 1 inch apart in the top layers of each roll. Brush with the remaining 3 tablespoons margarine. Bake in a 400 degree F oven 20 minutes or until phyllo is golden.
In a small saucepan heat brandy over medium heat. Add reserved peppercorn mixture, stirring with a wire whisk. Stir in 1 tablespoon half-and-half. Heat through. Spoon sauce onto individual plates. Place a strudel roll in center. Makes 2 servings.