Grate ginger and garlic, set aside. Cut meat of rolled shoulder into big chunks, brown from all sides in batches in the ghee, rendering down fat, remove meat from pan. Chop onions roughly soften them in the same pan, add the ginger and garlic, heat through, remove onions from pan. Add all the dried spices up to and including cayenne pepper. Heat until aromatic, do not fry or burn, remove from pan. Add with meat, water, bayleaf and tomato puree into slow cooker. Set on high.
Stir thoroughly and cook for at least 6 hours on high or until soft and tender but still in chunks. Mix together the joghurt with a few tablespoons of cooking liquid stir into the curry, then add garam masala. Cook for further 30 minutes on low heat, remove cinnamon sticks if using and the cloves.
