Blend together all the marinade ingredients in a food processor.
Trim the fat from the lamb and make deep cuts in the flesh.
Rub the marinade into the lamb and refrigerate for 24 hours.
Blend 70g of almonds with yoghurt and half the honey to make the rub.
Apply the honey rub to the lamb and refrigerate for 2 hours.
Preheat the oven to 225°C.
Place the lamb on a rack and roast for 15 minutes.
Lower the oven temperature to 180°C and roast for another 1 hour 40 minutes.
Baste the lamb every 20-30 minutes during roasting.
Scatter the remaining almonds and honey over the lamb and roast for 10 minutes more.
Rest the lamb under foil for 15 minutes before serving.