2 lb Ox Tails; Disjointed OR 2 ea Veal Tails 1 ea Onion; Medium, Sliced 2 T Vegetable Oil 8 c Water 1 t Salt 4 ea Peppercorns 1/4 c Parsley; Chopped 1/2 c Carrots; Diced 1 c Celery; Diced 1 ea Bay Leaf 1/2 c Tomatoes; Drained 1 t Thyme; Dried, Crushed 1 T Unbleached Flour 1 T Butter or Margarine 1/4 c Madeira In a 4-quart Dutch Oven brown oxtail and onion in hot oil for several minutes. Add water, salt and peppercorns; simmer uncovered for about 2 hours. Cover and continue to simmer for 3 additional hours. Add the parsley, carrots, celery, bay leaf, tomatoes, and thyme; continue simmering for 30 minutes longer or until the vegetables are tender. Strain stock and refrigerate for an hour or more. In a blender puree the edible meat and vegetables and reserve. Remove fat from top of stock and reheat. In a large, dry frypan brown flour over high heat. Cool slightly. Add the butter or margarine, blend. A little at a time, add the stock and vegetables. Correct seasoning and add madeira just before serving.