Cut the mutton into bite size pieces and place in a bowl. Pour on the vinegar and leave to marinade for 30 minutes. Chop the onion, then grind in a pestle and mortar with the garlic and ginger. Heat the oil and fry the onion, garlic and ginger. Add the chilli powder, paprika powder, turmeric, black pepper, coriander powder, cumin powder, fenugreek and curry leaves and stir fry for 3 minutes. Drain and remove the mutton from the marinade and add to the pan. Fry for 5 minutes, then pour in the coconut milk together with the marinade and bring to the boil. Cover the pan, reduce the heat and simmer for I hour, or until mutton is cooked. Just prior to serving sprinkle with the curry powder and add salt to taste. From "A taste of Sri Lanka" by Indra Jayasekera, Isbn #962 224 010 0