Veal Kidneys in Mustard Sauce

• 1 veal kidney, weighing 400–450 g (14–16 oz)
• oil, for cooking

Remove any membrane covering the kidney and cut down the length between the lobes to separate it into two parts. Turning each part over, cut down either side of the white fat and connective tissue and remove it completely. Now cut the kidneys into their lobes, which are each the size of a modest strawberry.

Heat a heavy sauté pan until quite hot. Add a film of oil, then add the unseason