First, heat oil in a pan and fry thinly sliced onions over medium heat until golden brown and crisp. Stir continuously to avoid burning, then set aside for later layering and garnish.
Next, in a large bowl, combine chicken with red chili powder, Kashmiri chili powder, garam masala, coriander powder, cumin powder, biryani masala, yogurt, tomato paste, garlic, ginger, green chili paste, and all other marinade ingredients. Mix well until the chicken is fully coated and let it rest for at least 1 hour or overnight for deeper flavour.
In the same oil used for frying onions, add whole spices and sauté until aromatic. Then add the marinated chicken and cook on medium heat until the masala thickens and oil begins to separate. Add dried plums (alu bukhara), cover, and cook until the chicken becomes tender and fully coated in rich masala.
Meanwhile, boil water in a large pot with salt, lemon slices, black cardamom, mint leaves, and kewra water. Add soaked basmati rice and cook until 80% done. Drain immediately to prevent overcooking and keep the rice fluffy.
In a heavy-bottom pot, start by adding a layer of chicken masala at the base. Then sprinkle fried onions, fresh coriander, mint, ginger, and lemon slices. Add a layer of partially cooked rice and repeat the process until all ingredients are used.
On the top layer, drizzle saffron-infused milk and a few drops of orange food colour. Add remaining fried onions, herbs, and garnishes for aroma and presentation.
Seal the pot tightly using a lid or dough around the edges. Cook on medium heat for 5 minutes, then reduce to low heat and steam for 15–20 minutes until the rice is fully cooked and aromatic steam develops.
Allow the biryani to rest for 10 minutes before opening. Gently mix from bottom to top and serve hot with raita and salad.