Chop half an onion and sauté in a little butter; when delicately browned, add five or six chicken livers and sauté them on both sides. Cover with well-seasoned chicken stock and let simmer until tender. Mash the livers fine with a wooden spoon and press them through a sieve; season with salt, paprica, mustard, or a dash of curry powder. Press into a cup, pour melted butter over the top, and set away in a cool place. When ready to serve, remove the butter and prepare the sandwiches after the usual manner.