Marinate mutton pieces with all the ingredients for marination & keep for 1 hour. Heat ghee in a pan/pressure cooker. Cook onions till it becomes brown. Add crushed ginger, garlic & green chillies and cook for 3-4 mins. Add tomatoes, salt (keep in mind salt is already added with mutton also) & stir. When tomato becomes soft add garam masala. After 3 mins, add marinated mutton pieces. Mix well. Add 1/4 cup water & cook (refer notes to see the pressure cooking details).
Grind the ingredients for white paste together with 2 tbsp water. Add the white paste when mutton is cooked. Add chopped coriander leaves (1-2 tbsp) and mix well. When the gravy becomes thick and mutton is tender remove from fire.
Rinse the rice a few times and soak for 25 minutes. Drain the water completely. Heat ghee in a wide and deep pan & splutter whole masala (cinnamon, cardamom and cloves).Fry the rice. When the rice starts cracking (around 4-5 mins) add hot water, salt & lemon juice. Cook the rice till the water is completely dried. Spread the rice on a tray.
Heat oil / ghee in a deep small pan. Fry the cashews and raisins till the cashews becomes brown and raisins plump. Add more oil / ghee, if required, and fry the onion till it becomes golden brown. Drain it on a paper towel.
Layering the Biriyani
Preheat the oven to 180 degree 10 minutes before baking the biriyani. Apply some ghee to a deep and wide baking dish. Spread one layer of masala first & a layer of rice on top of it. Repeat the same.The top layer should be of rice. You can drizzle ghee & sprinkle coriander leaves, mint leaves, fried onion, nuts and raisins in between the layers (on top of the rice). Spread a wet cloth over the dish while baking. Bake in the preheated oven for 25-30 minutes. Garnish with fried onions,nuts, raisins.