Combine flour, salt, pepper and dry mustard. Sprinkle mixture over steak and pound into the meat with your trusty meat mallet. Using a heavy skillet brown meat in hot oil. Combine water and worcestershire and add to browned meat. Cover tightly and cook in 325 degree oven for 1 hour or until tender. Heat mushrooms in a small amount of butter and serve on steak. Yummmm!