Hash eight medium-sized, cold, boiled potatoes ; place an ounce and a half of good butter in a frying-pan, add the potatoes, season with half a pinch each of salt and pepper, and toss them well in the pan for two minutes. Give them the shape of an omelet, and let them take a golden color, which will require five minutes. With a spoon take up all the butter which lies at the bottom of the pan ; slide the potatoes carefully on a hot dish, and serve.