Have your butcher mince the veal finely. Stiffen in butter, do not brown. As soon as no raw meat appears, take out with a skimmer, keep warm. Put the finely chopped onions and mushrooms into the same frying pan. Fry gently, stir frequently. When all the humidity has evaporated, leaving only butter in the pan, moisten with the vermouth. Cook over a moderate heat, reduce by half. Put in the meat again with the juice it gave out. Add the cream, salt, pepper, cook over a very moderate heat. To serve, thin the egg yolk with 1 tablespoon of sauce taken from the frying pan, pour the entire boiling contents of the frying pan into the serving dish and add the egg yolk. Stir to mix. Serve with spinach leaves in butter.
