Properly wash and cut the mutton into pieces.Wash and soak the rice for an hour as well. In the mean time, slice the onions and chop the green chillies, ginger, coriander leaves and mint leaves.
Keep half of both leaves to arrange on the rice. Chop the mint leaves only once they are ready to be used, otherwise, it will turn black or you can use whole mint leaves as well.
Heat oil in a kadai and deep fry the sliced onion till it turns golden brown. Drain on a kitchen towel paper .
Put the mutton pieces into a bowl and add the meat tenderizer, coat it properly and keep it in the fridge for 6-8 hrs .
After this time, take out the bowl from the fridge and add the curd, garlic paste, ginger paste, chopped green chillies, red chilli powder, turmeric powder, salt ,garam masala (1 tsp) and mix well.
Add half of the fried sliced onions and chopped coriander and mint leaves. Once again keep this marination in the fridge for 30-40 mins. Boil the water in another pan to cook the rice. Bring it to a boil and cook till its 3/4 done, note that the rice should not be fully cooked.
Strain the rice and keep aside. Take a thick pan to prepare the biryani, add ghee (3 tbsp) in a pan to heat, add the mutton and put the rice on top of it. Then top it off with fried sliced onions, thinly sliced ginger and garam masala powder.
Next, add the chopped coriander leaves and mint leaves. Pour in half the pure ghee on top, add the saffron soaked in warm milk, then pour in rose water and kewra water (don't use much as it gives a bitter taste). Cover this vessel with a lid.
Seal the lid with a wheat flour dough or cover it with an aluminium foil so that the steam is packed inside. Cook on a high heat for five minutes then lower the heat. Keep this on a tawa and cook on a low heat for 45-50 minutes.
After 45-50 mins, turn off the gas and leave the biryani pot on the tava for another 10-15 mins.
The biryani is ready to be eaten. Serve it hot to enjoy!