Divide 1/2 cup sweet butter into 3 parts. Put the first part in the top of a double boiler with 2 eggs yolks and 1 tablespoon strained lemon juice, and stir with a wire whisk until the butter is melted. Add the second part of the butter, and, as the mixture thickens, the third part. When the butter has melted, and the whole is well mixed, add gradually 1/3 cup boiling water, continuing to whisk constantly. Cook in the double boiler for 1 or 2 minutes longer, then season with salt and pepper to taste. If the mixture should curdle, beat in another 2 tablespoons boiling water or 2 tablespoons heavy cream.
