For the lamb: Add the oil, rosemary, thyme, garlic and a pinch each salt and pepper in a bowl, and pour over the lamb chops. Marinate the lamb in the refrigerator overnight.
Preheat the grill to 280 to 320 degrees F. Grill the lamb to desired doneness, about 4 minutes on each side for medium rare.
For the sauce: Combine the demi glace, wine, preserves and orange zest in a saucepan and bring to a boil. Then simmer for 5 minutes.
Serve the lamb chops with the Madeira sauce.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.