Yolks of 5 eggs, 5 tablespoonsful of vinegar. Put the vinegar in stew pan and while it is heating, beat the yolks. When the vinegar boils pour it over the eggs. Put the whole in double boiler and stir until thick, add 1 tablespoonful of butter. When cold thin with cream. Season with salt and pepper, black or red, and a little mustard.