Blend the flour and butter as in White Sauce, only letting it become slightly yellow. Add by degrees the boiling water, and season to taste. a tablespoonful of White Wine is a fine addition. Add the juice of half a lemon, and a tablespoonful of chopped parsley. Let it simmer for about ten minutes, and take from the fire, and add the well-beaten yolks of two eggs. Serve immediately with any boiled fish or meats.