Cook the onion, carrot and celery in the butter and oil over moderately high heat, stirring for 7 to 10 minutes or until vegetables are golden. Add flour and cook over moderate heat, stirring for 2 minutes. Stir in stock, 4 cups water and wine. Bring to a boil. Add turkey carcass broken in pieces, parsley, thyme, bay leaf, and peppercorns. Simmer soup, partially covered, skimming any froth as it rises to the surface, for about 1 1/2 hours. Strain soup into heated tureen, pressing hard on the solids. Serve or cool and store.