To make the beresta, heat 1 cup of cooking oil in a pressure cooker. When it is hot, put 2 pieces of onions (medium sized, finely sliced). (Pro tip: Use a pressure cooker as you will need to pressure-cook the mutton. It reduces hassles).
Stir it continuously and fry it on a medium to high flame until it turns golden brown. (Pro tip: Do not fry the onions at a very high flame or else it will burn and render a bitter taste, and a low flame will make it mushy).
When done, drain and remove the fried onions on a plate.
Add 1 tsp of garam masala powder, ¼ cup chopped mint leaves, and ¼ cup chopped coriander leaves to it and mix them nicely. Keep the plate aside.
Now, take out 2 tbsp of cooking oil from the pressure cooker and keep aside.
Heat the remaining oil in the pressure cooker on a low flame and add ½ tsp of black cumin seeds, ½ tsp of black pepper, 1 tsp of cumin seeds, 4 pods of green cardamom, a piece of star anise, 2 sticks cinnamon (inch size), 1 piece of black cardamom, and 2 pieces of bay leaves. Fry them slightly for a minute.
At this stage, add 2 pieces of onions (medium sized, sliced finely). Stir them and fry until they turn light golden brown.
Then add 4 pieces of whole green chilies and 2 tbsp of ginger garlic paste. Stir and cook them nicely until the raw smell is gone.
Now, add 1 kg of mutton to it. Turn the flame to high immediately.
Stir and cook the mutton nicely until it changes color, becomes dry and the oil separates. Then add ½ tsp of turmeric powder, 1 tsp of red chili powder, 1 tsp of cumin seeds powder, 1 tsp of coriander seeds powder, 1 tsp of garam masala powder, and 1.5 tsp of salt to it.
Stir and cook it nicely with the powdered spices until it changes color. Now, turn the flame to low and add ½ cup of whisked yogurt and mix it. (Pro tip: Yogurt will curdle if you add it when the flame is high).
When you see the oil separating, add a fistful of finely chopped coriander leaves. Mix it nicely and cook it on a medium flame.
Finally, add 1 cup water to it when the oil starts to separate and mix nicely. Let it come to a boil. (Pro tip: Do not add too much water. Since the mutton is fresh, it will release its own oil and moisture).
Now cover the pressure cooker and let it cook until the gravy becomes thick. Check the consistency. (Pro tip: Ideally, you should cook the mutton for 30 to 35 minutes or up to 4 to 5 whistles).
If the consistency is thick enough, add half of the remaining beresta to it that you have made earlier. Mix it nicely. Cover the pressure cooker and keep it aside.
Now, to make the rice, boil 4 liters of water. Then add a cinnamon stick (inch size), 2 pieces of bay leaves, and a piece of star anise. Also, squeeze 1 tsp of lemon juice and put the lemon as well along with 2 tsp of salt and 1 tbsp of cooking oil.
Let them cook for 2 to 3 minutes before removing them from the boiling water.
Now, add 1 kg basmati rice (pre-soaked for 30 minutes).
Cook the rice till it is 70 to 80% cooked. Check the doneness.
Now, in a separate patili, spread the oil that you have removed earlier after cooking the beresta.
Put the hot rice in it. Spread it to create a layer.
Now, put the mutton and spread it to make the next layer on top of the rice.
Now, spread the beresta on top of the mutton.
Create another layer with the remaining rice on top of the mutton.
Now, in a separate bowl take ½ cup of hot milk and mix ¼ tsp of saffron, ½ tsp turmeric powder, and 1 tsp kewra water. (Pro tip: Use hot milk as that will remove the raw smell of turmeric powder. You can use a few drops of yellow food color in place of turmeric powder if you want).
Mix everything nicely and pour it on the rice.
Now, add 2 tbsp of clarified butter (ghee) to it as well.
Finally, put the remaining beresta on the rice. Cover it with a lid and cook the biryani for 15 to 20 minutes in a very low flame.
After 20 minutes, remove the lid, mix the biryani very carefully from the sides, working down gently.
Your homemade tasty and spicy mutton biryani is ready now. Take it out on a plate and serve it hot.