Trim the kidney leaving it covered with a thin layer of its own fat. Cut it across its width into 5 or 6 round slices; season these and shallow fry them quickly on both sides in hot butter. Remove and place on a plate.
Deglaze the pan with
Arrange the slices of kidney in a circle in a timbale or on a dish and coat with the prepared sauce. Place a nice bouquet of buttered asparagus tips in the centre with a dozen slices of truffle on top.