Trim all fat and silver skin from lamb.Prick lamb thoroughly with a sharp knife or large fork or cut small slits all over lamb with a sharp knife.
Place the lamb in a deep baking dish, spread lemon juice all over lamb and rub it into the slits.Cover and marinate for an hour.
Combine garlic paste, salt, black pepper, coriander, nutmeg, cumin and yogurt in a small bowl. mix well.
Pour the marinade over the lamb and coat well all over.
Cover and place it back in the refrigerator for 6-8 hours or preferably over night.
Prepare the grill and grill lamb on an oiled rack set 5-6 inches over glowing coals for 10-15 minutes on each side.
At the end of cooking time brush lamb with oil.Serve it with Nan and Chutney.