
Put the olive oil and the butter in a hot roasting pan. Add the lambs kidneys, roast on the side, then season the kidney. Remove the kidneys; add the shallots, the honey and the dry mustard. Deglaze the pan with the champagne vinegar, the white wine and the veal stock. Cook the shallots until soft. Add the chopped chives. Replace the kidneys in the sauce and reheat.
Serve the kidneys with potato rosti.