Cut meat into large cubes, brown on all sides in heated butter. Remove meat add onions, diced bacon and quartered mushrooms to remaining juice together with sugar and brown slowly. Remove vegetables and bacon sprinkle with flour, cook slowly until brown. Pour wine into flour mixture; bring to a boil stirring constantly. Add browned meat; and sufficient stock to cover. Season to taste. Cook in slow oven for 1 hour. Add onions, mushrooms, bacon. Continue cooking until meat is tender, thicken if necessary.
