In a 10" skillet, brown ground beef and onion until juice evaportes. Remove from heat. Drain fat. Stir in broccoli, cheese, sour cream, bread crumbs, salt and pepper. Preheat oven to 350 F. On wax paper, place 1 sheeet filo. Brush with melted margarine. Repeat with all of Filo. Starting at short side of Filo, evenly spoon ground beef mixture to cover half of rectangle. From ground been end, roll, jelly-roll style. Place roll, seam-side down on cookie sheet. Brush with rest of melted margarine. Bake at 350 F. for 45 minutes until golden. Cool for 15 minutes on cookie sheet to ease cutting.