A rich, deeply spiced curry slow-cooked until the aromatic tomato and onion reduction clings intimately to the tender cuts.
Heat the mustard oil until smoking and fry the onions until deep brown.
Add the ginger-garlic paste and fry, then add the mutton and sear on high heat until sealed.
Add the coriander powder, cumin powder, turmeric, and tomatoes and fry for 8-10 minutes until the oil separates.
Add 1/2 cup water, cover, and cook on low for 60-90 minutes until the mutton is tender, stirring occasionally.
Uncover and bhunao until the gravy clings thickly to the meat.
Sprinkle the garam masala, rest for 10 minutes, and serve with roti or rice.