Soak the veal sweetbread in cold water for 2 hours to remove any spots of blood, then blanch in boiling salted water for 10 minutes. Cool with cold water, skin very well. Fry the quails in 1 tablespoon butter over a moderate heat to avoid browning the butter. Take out. Sweat the finely sliced mushrooms, rubbed with lemon, in the same saucepan until their water evaporates. Put in all the ingredients together with the pieces of ham, moisten with the Champagne, the Fine de Champagne and a few tablespoons of the sweetbread cooking water, add the bouquet garni, salt, pepper, cover. Cook over a very low heat for 30 minutes. Take out the quail and the sweetbread, keep them warm. Remove the bouquet garni and the ham which is used only to flavor the sauce, skim the fat off the sauce if need be. Add the flour dissolved in a little cold water, thicken, then add the tomato paste, the cream and the truffle cut into very thin sticks. Bring to a boil, adjust the seasoning, put in the quail and the sweetbread again, cook for a further 10 minutes without allowing to boil. To serve, arrange the quail and the pieces of sweetbread alternately, coat with the sauce.
