A rich, deeply spiced curry slow-cooked until the aromatic tomato and onion reduction clings intimately to the tender cuts.
Marinate the mutton in the yogurt, ginger-garlic paste, half the garam masala, and salt for 2 hours.
Fry the onions in the ghee, add the mutton with its marinade, and bhuna over medium heat until the masala is dark and the oil separates.
Add 1 cup hot water, cover, and cook until the mutton is tender, about 40 minutes.
Parboil the soaked basmati in salted water until 70% done and drain.
Layer the mutton masala, rice, remaining garam masala, mint, and saffron milk in a heavy pot.
Seal and cook on the lowest heat 20 minutes; rest 10 minutes before serving.