In a large bowl combine ground beef, bread crumbs, water, pepper, egg and onion soup mix. Mix thoroughly.
Roll mixture out 1/2-inch thick, to a 10-by-6-inch rectangle between 2 sheets of waxed paper. Turn out onto cookie sheet, removing paper from both sides. Using finger or spoon handle, poke holes in meat.
Bake in preheated 400-degree oven 10 minutes. Remove. Pour off any fat. Cut meat into 20 squares to fit rolls. Place one piece of meat into a roll and top with hamburger dills if desired. Serve hot.