1 1/2-2 kg/3 1/2-4 lbs. leg of lamb

Put the following ingredients into an electric food processor or liquidiser and blend until smooth: 1-inch cube of root ginger, peeled and coarsely chopped 4-6 cloves garlic, peeled and coarsely chopped 1 med.-sized onion, coarsely chopped 1 fresh green chili 2 tbsp. fresh mint or 1 tsp. dried or bottled min

Add the following ingredients and blend for a few seconds longer: 1 tsp. ground cumin 1 tsp. garam masala 1 tsp. ground turmeric 1 1/4 tsp. salt or to taste

Grind the following 3 ingredients in a coffee grinder: 1 tbsp. sesame seeds 2 tbsp. desiccated coconut 25 g/1 oz. ghee or unsalted butter 450 g/1 lb. med.-sized potatoes, peeled and halved

Liquidise to a smooth paste: 50 g/2 oz. raw cashews 50 g/2 oz. seedless raisins, soaked in a little warm water for 30 minutes

Remove as much fat as possible from the meat and lay it flat on a board. Make deep incisions from top to bottom at about 1/4-inch intervals. These incisions should be as deep as possible, almost down to the bone. Turn the leg over and repeat the process.

Mix the yogurt-based mixture with the ground spices. Rub this marinade into each incision, and then fill the incisions with it. Rub the remaining marinade all over the surface of the leg of lamb on both sides. Place in a covered container and leave to marinate in the refrigerator for 48 hours. Turn it over about every 12 hours.

Preheat the oven to 230 degrees C/450 degrees F/Gas Mark 8. Place the leg of lamb on a roasting tin, melt the ghee or butter and pour it over the meat. Cover the meat with aluminum foil or use a covered roasting dish and cook in the center of the oven for 20 minutes.

Reduce heat to 190 degrees C/375 degrees F/Gas Mark 5 and cook for 30 minutes. Now add the potatoes and spoon some of the spied liquid over them as well as over the meat. Cover and cook for a further 35-40 minutes, basting the meat and the potatoes occasionally.

Now pour the liquidised nut mixture over the meat. Cover and return the meat to the oven for about 30 minutes, basting the meat and the potatoes as before. Transfer the meat onto a serving dish and arrange the potatoes around it. Spoon any remaining liquid over the mat and the potatoes. The meat is served cut into chunky pieces rather than thin slices.