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 it just smokes; crackle the black cardamom and asafoetida.
Add the lamb and sear on high heat until browned all over.
Lower the heat; add the ginger-garlic paste, fennel, Kashmiri chili, and dry ginger; fry 2 minutes.
Add the whisked yogurt a spoonful at a time, stirring so it does not split.
Add 1 cup hot water; cover and simmer 90 minutes until the lamb is tender.
Uncover and reduce until the oil floats on top; serve with steamed rice.