Leave two dozen live crayfish under a running tap for five or six hours to remove the sand; drain them, and dry on a cloth. Put in a stewpan two ounces of butter, half a carrot, one good sized onion, a strip or two of celery, and half a leek, all cut up into small pieces, twenty-four crushed black and white peppercorns, half a blade of mace, and a good bunch of herbs (thyme, parsley, and bayleaf). Lay the crayfish on this, cover the pan down, put it on a quick fire, and let it fry for fifteen minutes, constantly shaking the pan; then add half a pint of white wine, and a pint of good, well-flavoured fish stock. Cook together for twenty-five or thirty minutes, boiling very gently. Put two ounces of butter in a pan and fry with two ounces of flour; strain the liquor from the crayfish, reduce it to three quarters of a pint, then add it to the flour and butter. Crack the shells of the crayfish, remove the flesh from the bodies and claws, keeping them as whole as possible to garnish the sauce. Scrape the meat from the heads, pound it with two ounces of live lobster spawn, and add this pounded mixture to the sauce, with a teaspoonful of essence of anchovy and a few drops of carmine if lobster spawn is not to be had. Stir the sauce till it boils, then add half a gill of cream, tammy, re-warm in the bain marie, add the claws and bodies of the crayfish, and serve.
This sauce is excellent with plainly boiled salmon, turbot, codfish, soles, doreys, brill, &c.