Cook 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 ti rises to surface, for about 1.5 hours. Strain soup into heated tureen, pressing hard on the solids. Serve or cool and store.