Brain soak for 1 hour in acidified with vinegar cold water, peeled and cut into slices that salting, scatter with pepper and rolled in flour. Fry in a part of the heated butter. Cleaned and sliced ​​mushrooms sauté in remaining butter. Add the wine, sugar, lemon juice, grated lemon rind and 1 tsp flour mixed into a little cold water. Boil the sauce and boil for 5-6 minutes on low heat, add salt and retired from the fire. Slices of the brain is divided into portions, pour with fat, which are fried, remove and pour a little of the mushroom sauce.