(Recipe #40, page 134)
Put the fish’s tail in its mouth and place it in not too large a casserole (to keep the broth from becoming tepid) with equal parts of vinegar and cold water, some onions, two bay leaves, some peppercorns, a half to whole parsley root, and the necessary salt. Set it on the stove and boil until done. Carefully remove the fish to a heated platter, pour the following sauce over it, and cover.
Prepare some mushrooms, crayfish tails, and crayfish butter. Stir 1 spoonful of flour into a knob of foaming butter; meanwhile stir 10 egg yolks into a scant quart of strong bouillon. Pour the bouillon into the flour and butter and let it come to a boil, constantly stirring. Add the mushrooms, crayfish tails, and butter, and a bit of lemon juice, and pour the sauce over the fish.
Translated by David Green.