Turn your slow cooker to low. 

Melt the butter and oil in a large frying pan. Brown the lamb in batches over high heat. Remove from the pan and set aside. 

Place the onions, apples, bananas, curry powder and ground cumin in a bowl and mix. Add to the hot frying pan and cook over medium heat for 5 minutes. 

Return the meat to the pan, add the stock powder, salt and pepper to taste and enough water to just cover the mixture. Bring to a gentle boil and then transfer to your slow cooker. 

Cook for 6-8 hours on low or 4 hours on high. The meat should be very tender. 

Garnish with coriander and serve with steamed jasmine rice and poppadoms.

Oven method: This dish can also be made in the oven as per the method above in a oven proof casserole dish. Cook for 3 hours on 150C fan bake, or until lamb is tender.