For twenty-four sandwiches take one tureen of foie gras. Remove the fat, and mash the foie gras to a perfectly smooth paste, adding gradually four tablespoonfuls of soft, not melted, butter; add a dash of cayenne and a half teaspoonful of salt and about ten drops of onion juice, and press the whole through a sieve. Cut slices of bread into fancy shapes and toast; crescents are very pretty. Cover each slice thickly with this paste; garnish with hard-boiled white of egg, cut into diamonds or tiny crescents, and olives cut into rings. Arrange neatly, and they are ready to serve.