Clean the Mutton really well and then in a big vessel take the mutton pieces to this add in Ginger Garlic paste, Red Chilli powder, Turmeric Powder and Salt, Mix everything together.
Next add in the curd and mix it once again .Allow it to Marinate for about 30 mins.After the marination transfer the marinated mutton to a pressure cooker and add little water for the mutton to get cooked.
Pressure Cook the mutton for about 7-8 whistles or till the mutton is fully cooked and set it aside. Take a pan and add in the Oil once it heats up add in the Whole spices mentioned under the To Temper in the ingredients table. Let it sizzle. Next add in the sliced onions.
Cook till the onions caramelizes and become brown, set some onions aside for garnish during the Dum Process. Along with the remaining onions now add in the tomatoes and cook till it leaves oil in the side.
Now add in the cooked Mutton in the pan, Check for salt and spice and add if anything is required .Cook for few mins till the gravy becomes thick and switch off the flame. Cook the Basmati Rice and set aside (click https://happietrio.com/how-to-cook-basmati-rice-perfectly/ to see how to cook Basmati Rice for Biryani). Clean the Coriander leaves and Mint Leaves and set aside. Soak the Saffron strands in the Milk and keep it ready .to the Dum process we need a big vessel with a lid. I have cooked using charcoal Dum Method .Same can be done in Pressure Cooker as well (click here for Pressure Cooker Dum Process) .Now take the big vessel and set the cooked mutton as the first layer of the Biryani.
Top the Mutton with half of the cooked Basmati Rice. Upon this Sprinkle Saffron Milk and the spread with half of the cleaned coriander and Mint Leaves and sprinkle the reserved the Onions as well. Top the leaves with the remaining cooked Rice.
Once again sprinkle the Saffron Milk, add in the coriander leaves and Mint Leaves and then the Onions. After this cover the vessel with the Lid and keep the Charcoal Dum on top. If possible seal the lid with Chapatti dough. This prevents the flavours from going outside the vessel.
Continue the Dum for about 25 mins and then open the lid, everything would be beautifully cooked with full of flavours. Carefully mix the Masala and Rice and serve hot with Onion Raita and Gravy.