Cut the pike perch fillet, holding the knife obliquely, into thin slices, put in a deep frying pan, pepper, add the wine and a little broth.
Make a dumpling mass from the remains of pike perch. Put it in a pastry bag and squeeze a ring out of it onto each piece of zander.
Cover the pan with a lid and cook the fish over low heat until cooked.
Boil the crayfish, remove the necks and claws, start the frames and boil them in salted boiling water.
Stew the champignons in oil. When everything is ready, put in a deep dish: mushrooms in the middle, fillets all around mixed with crayfish tails; pour all the sauce, top, in the centre, garnish with stuffed carcasses and green lettuce.
Making the sauce
Grind 50 g butter with flour, dilute with hot broth, salt and boil.
Grind the rest of the butter, yolk and cream and add to the sauce.
Stir well, strain through a fine sieve, put on the steam and heat well, not letting it boil.