Heat oil/ghee in a large pan and fry onions, until quite dark brown. Take out & keep aside.
In the same pan heat oil (2 sp); add all whole spices (cloves, cardamoms, cinnamon, black peppers, bay leaves as required), ginger and garlic paste (1sp). Fry them for a minute.
Add medium sized mutton pieces (250g), add salt, chilli powder. Stir fry until meat is nicely browned on all sides.
Now add tomatoes (1/2 cup), yoghurt (1/4 cup), coriander and mint leaves (few), sliced green chillies (4-5), Cook this for 15-20min on medium flame.
Take water (500ml) boil, add salt, mint & coriander leaves, to this add basmathi rice (250g) and boil briskly, with lid off, until 2/3rd done.
Strain the water; run a little cold water over it,
Heat a large dish or pan on the stove; spread the rice in a layer at the base of the pan, sprinkle saffron water and rose water on it and spread prepared curry. Add deep fried onion, ghee (1sp), and food color (yellow or orange) mixed water (2-3drops), coriander leaves, and fried cashew nuts.
Repeat this process until the prepared rice and curry finish. Cover the pan with a tight lid. Keep this on medium flame, until the rice is fully done.
Serve the hot lamb biryani with ritha by adding lemon juice.