Have butcher score a flank steak, well, on both sides. Sprinkle with flour and salt both sides. Dot with butter, place in oblong baking pan. Over meat, place thick layer of sliced raw potatoes, lay small peeled onions on top, and if desired, whole carrots around edges. Decorate with rings of green pepper. Salt the vegetables. Over all. pour strained canned tomatoes. Cover tightly and cook slowly in oven until meat and vegetables are tender, about 2 hours for a large flank. A half hour before serving, uncover to allow browning.