In a large bowl combine yogurt, ginger paste, garlic paste, red chili powder, turmeric, garam masala, salt, and lemon juice. Add the mutton pieces and rub the marinade into meat thoroughly. Cover and refrigerate for at least 2 hours, preferably overnight for best flavor.

Prepare whole spices and onions

Heat 2 tablespoons oil in a heavy-bottomed pot or pressure cooker over medium heat. Add whole spices (bay leaf, green cardamom, cloves, cinnamon, star anise, black cardamom) and sauté for 30 seconds until fragrant. Add sliced onions and sauté, stirring frequently, until golden brown and caramelized (about 12–15 minutes). Remove one-third of the browned onions and set aside for layering (these become birista).

Brown the mutton

To the pot with remaining onions, add remaining oil and increase heat to medium-high. Add marinated mutton and sear for 6–8 minutes, stirring occasionally, until edges brown. Add chopped tomato and slit green chilies, cook 3–4 minutes until tomato softens.

Simmer or pressure-cook

Add chopped cilantro and mint and pour 400 ml water into the pot. Stir, bring to a simmer. If using a pressure cooker, cook on medium heat 20–25 minutes (2–3 whistles) until mutton is tender. If using a pot, cover and simmer for 1.5–2 hours until meat is fork-tender, adding water as needed. Adjust salt and spice; the mutton should be well-cooked with a thickish gravy — not too soupy, as some moisture is needed for final dum.

For the rice and layering

Prepare saffron

Soak saffron threads in warm milk and set aside for at least 10 minutes to release color and aroma.

Parboil rice

Bring 2.5 liters water to a rolling boil in a large pot. Add 2 teaspoons salt and a tablespoon of ghee. Drain soaked rice and add to boiling water. Boil uncovered until rice is about 70–80% cooked (grains still have a slight bite) — about 6–8 minutes depending on rice. Drain rice in a colander and spread briefly to stop cooking.

Layer mutton and rice

Reduce the mutton gravy heat so it simmers gently. In a heavy, wide-bottomed pot (dutch oven) or use the same pot if cooker has space, start layering: spoon half of the cooked mutton and some gravy evenly across the base. Sprinkle half of the reserved fried onions (birista), half of the chopped cilantro and mint, and a tablespoon of ghee. Spread half of the parboiled rice over the meat layer. Repeat with remaining mutton, fried onions, herbs and rice, finishing with the top layer of rice.

Add saffron and seal for dum

Drizzle the saffron-infused milk evenly over the top rice layer and dot remaining ghee. Scatter roasted cashews and raisins if using. Cover the pot with a tight-fitting lid. Seal edges with dough or wrap lid with a clean kitchen towel to trap steam (optional). Cook on very low heat for 25–30 minutes (dum) to allow flavors to meld and rice to finish cooking through steam.

Rest and serve

Turn off heat and let the biriyani rest, sealed, for 10 minutes. Gently fluff the rice from the edges using a wide spatula, mixing layers slightly to distribute meat and rice while preserving some distinct layers. Serve hot with raita, salad, and extra fried onions on top.