Grind the meat with bread. Add the onions which have been sauteed in the drippings. Season with salt and pepper. To prepare dough, mix the egg with the flour, add a dash of salt and as much water as needed to knead a smooth loose dough. Roll out as thinly as you can. Cut out 2 1/2 to 3 inch squares. Put a little of the stuffing on each square. Fold to form a triangle, pinch the edges together. Cook in a large kettle with boiling salted water on high heat for 5 minutes. Remove with a colander spoon to a warmed serving platter. Add the bread crumbs to the butter and fry for a few minutes on low heat. Pour over the pierogi.