• As the process is elaborate; I am writing down phase by phase to help you to understand what to do next.

Making of Biriyani Masala:

• Dry roast all the spices mentioned under the head of Biryani Masala.
• Once cooled, make a powder of the spices.
• Around 2 tablespoon of this powder will be used in the Biryani.
• Store the masala in an airtight container for further use.

Marinating the Mutton (stage 1 & 2)

• 
• Marinate mutton with papaya paste and 1 teaspoon salt for 8 hours.
• After 8 hours, mix the Onion paste, ginger paste, Garlic paste, green chili paste, and crushed Birista along with plain curd, sweet curd, and sahi jira paste (optional). Turmeric powder, tomato ketchup with ¼ teaspoon salt.
• Add 1 teaspoon of Biryani Masala as well and marinate the mutton with the spices for 2 hours.

Making of Birista and Fried Potato:

• 
• Finely chop Onion.
• Heat oil in a pan.
• Fry the onion till they are crisp.
• Strain from the oil.
  
• Peel and cut potatoes in half. If using medium-sized potatoes keep those wholes.
• Marinate potatoes with a mixture of yellow food color and ¼ teaspoon salt.
• Heat the same oil used for making Birista.
• Temper the oil with 1" Cinnamon, 1 Black Cardamom, 2 Cloves, and green cardamom.
• Fry potatoes until they are golden in color and 70% cooked.
• Add ½ teaspoon Biryani Masala to it as well.
• Strain fried potatoes from the pan.
• Use the same oil for cooking mutton.

Cooking the Mutton:

• Heat Ghee and ½ of the spiced oil used in frying the onion and Potato in a deep-bottom pan and temper it with bay leaf and dry red chili, mace, nutmeg, cinnamon, and cardamom.
• Add the marinated mutton with the marinade and mix.
• Cover the pan with a lid and cook over a low flame for around 1 hour or till the mutton is done 70%.
• You do not need to add water. Mutton will be cooked in its own water.
• Once the cooking is done, the pan will have cooked meat and the oily substance separated.
• This oily substance is known as "Tahr."
• Separate the Tahr when the meat is hot from the pan and keep it aside.
• This makes the biryani flavorful.

To make Akhni Water and cook the rice:

• 
• Take 2 liters of water in a vessel.
• Take the spices mentioned under the head "Akhni Masala" and make a "Potli using a fresh cloth with the spices.
• Boil the spice potli along with the water for around 30 minutes.
• The water will change color and will turn light brown.
• Meanwhile, wash rice 2-3 times under running water.
• Soak rice for the time water is boiling.
• Add 2 teaspoon salt to the boiling water and also the soaked rice.
• Cook till the rice is done 70%.
• Switch the flame off and drain the water.
• Spread cooked rice over a plate.

Assembling the Biryani:

• 
• Warm the Tahr before using it again and mix with the remaining oil from frying the onion and potatoes.
• Mix Keshar and a pinch of yellow food color with milk after crushing it using a mortar and pestle.
• Take 2 tablespoon Ghee and coat the inner side of a handi with the ghee.
• Take around 15 Bay leaves and place those.
• Pour the cooked mutton with the gravy.
• Top it with ⅓ of the cooked rice.
• Sprinkle ⅓ of the Biriyani masala, followed by ⅓ of the keshar milk and a drop of mitha Itr, followed by 1 tablespoon of Tahr and some ghee.
• Add ⅓ Rice again followed by boiled Egg (if using) and Fried Potatoes.
• Sprinkle ⅓ of the Biriyani masala, followed by ⅓ of the keshar milk and a drop of mitha Itr, followed by 1 tablespoon of Tahr and some ghee again.
• Add Keora Water as well.
• Again, add the rest of the rice, followed by crumbled khowa and aloo Bukhara.
• Sprinkle ⅓ of the Biriyani masala, followed by ⅓ of the keshar milk and a drop of mitha Itr, followed by the remaining ghee and Tahr.
  
• Cover the Handi with a lid and seal it with Soft Whole wheat Flour dough.
• Keep the flame on the lower side and place a Tawa over the heat.
• Place the Handi on the top of the Tawa and cook for around 15 minutes.
• The dough will be tough after 15 minutes, and you can break it using your fingers.
• When the dough is crumbly, your Biryani is basically ready.
• Switch the flame off and do not open the seal for 15 minutes.
• After 15 minutes, open the seal.
• Using a spatula, lightly mix the Biryani while serving, but not before that.

If using Aluminium Foil to seal

• Cover the vessel with foil (2-fold) and then place the lid.
• The rest of the process is the same.
• In the video, I have shown how to follow this process.