Wash, clean and cut the mutton into small pieces. Peel and slice the onions, coriander leaves and mint. Peel ginger and garlic. Grind ginger, red chillies, garlic and nuts into a fine paste. Heat fat. Fry onions till golden brown and crisp. Remove. Add bay leaf, ground masala, and fry. Add tepid water and cook with lid on till meat is tender and gravy is thick. Boil rice till three-fourths cooked. Add salt. Strain curds with a fine piece of muslin. Add powdered cloves, cinnamon, cardamom, sweet cumin, turmeric, chopped green chillies, coriander leaves and mint. Add lime juice and mix well. Add curds mixture to mutton. Stir well. Dissolve saffron in some milk and sprinkle over half the rice. In a strong pan put in layers of rice, mutton and fried onion. Repeat till all ingredients are used up. Pour remaining milk and fat over the rice. Cover pan and seal edges with wheat flour paste. Place in an oven 143 C (300F) for one hour and serve very hot.