BOILED MACKEREL À LA BOLONAISE
Clean four fresh mackerel, remove the heads and tails and cut in halves crosswise. Put into a saucepan with sliced onions, a bunch of parsley, salt and pepper, a little white wine, and enough boiling water to cover. Cover with buttered paper and simmer for fifteen minutes. Take out the fish, strain the broth, and thicken a pint of it with two tablespoonfuls each of butter and flour cooked together. Add two tablespoonfuls of butter, a teaspoonful of chopped parsley, and a little tarragon vinegar. Pour over the fish and serve.