Marinate the lamb:
In a large bowl, combine lamb with yogurt, ginger-garlic paste, turmeric, cumin, coriander, chilli powder, lemon juice, and salt. Mix well, cover, and marinate for at least 1 hour (overnight for deeper flavour).

Cook the rice:
Rinse the basmati rice in cold water until the water runs clear. Bring a large pot of salted water to a boil with bay leaf, cloves, cardamom, and cinnamon. Add the rice and cook until about 70% done (still slightly firm). Drain and set aside.

Cook the lamb:
Heat ghee or oil in a large heavy-based pot. Add onions and sauté until golden brown. Add the marinated lamb and cook for 10–15 minutes, stirring often, until the lamb starts to brown and release juices. Add the tomatoes and garam masala. Cover and simmer on low heat for 30–40 minutes, or until the lamb is tender.

Layer the biryani:
Reduce heat to low. Remove half the lamb and set aside. Layer half of the rice over the remaining lamb in the pot. Sprinkle with some coriander, mint, and a bit of saffron milk. Add the rest of the lamb, then top with the remaining rice, herbs, and saffron milk.

Steam (dum cook):
Cover the pot tightly with a lid (or seal with foil), and cook on the lowest heat for 20 minutes. Let it sit for 5 minutes before serving.

Serve:
Fluff gently with a fork. Serve hot, garnished with fried onions and extra herbs. Enjoy with raita or a fresh cucumber salad.