Required: The yolks of four hard-boiled eggs. Two teaspoonfuls of anchovy essence. A little lemon-juice. Half an ounce of butter. Salt and pepper.

Work all the ingredients together with a wooden spoon until they are in a smooth paste. If possible, rub the mixture through a sieve, though it is not necessary. Season it carefully to taste. It may only require very little salt, anchovy essence frequently being very salt.