Wash clean and cut mutton into 2 inch pieces. Mix with biriyani Masala and set aside. Peel and cut onions into thin slices. Clean, peel and chop ginger and garlic. Beat the curd and mix with the chopped ginger, garlic and slit chillies. Heat oil in a pan fry sliced onions till light golden brown and remove. Add mutton pieces with masala and fry till oil separates from the masala. Add hot water, salt and cook till the mutton is tender and gravy thick. Pressure cook if needed. Taste for seasoning. Clean wash and strain the rice. Boil 8 cups (2 liters) of water. Add salt and a dash of lime juice. Add rice and boil till half done. Strain the rice. Mix finely chopped mint and coriander leaves with curds. Add this mixture to the mutton. Add cashew nuts and mix well. Check for seasoning. Dissolve saffron in warm milk and sprinkle over half the rice. In a heavy bottom cooking pot, layer mutton, rice and fried onions. Repeat the layers and top with rice layer. Pour remaining milk and ghee over the rice. Sprinkle fried onions and kismis. Cover with a tight fitting lid and bake at 140oC or 300oF for 30 -40 minutes. Biriyani can be cooked on top of a slow fire for about 50 to 60 minutes. Serve hot garnished with fried onions and kismis.