Sauce d’Argenteuil:—Pound three hard-boiled yolks of egg
to a paste and work into it a sherry glassful of salad oil, a tea-
spoonful of mustard, a saltspoonful of pepper, and one of salt;
mix thoroughly, and add a tablespoonful of cold velouté,
finishing with a teaspoonful of tarragon vinegar and a dessert-
spoonful of chopped parsley. Serve very cold.