Clean the kidneys, remove the skin, the fat and the nerve in the middle; slice them in two sideways, but without parting the two pieces. Put through a silver skewer. Salt and paint with melted butter. Grill for a few minutes. When ready, serve with a maître d’hôtel sauce, or put on each the following mixture: a piece of butter the size of a walnut, a little parsley and quarter of a head of garlic, well worked together.