Bone-in goat shoulder marinated in yoghurt and shahi garam masala, then slow-braised in mustard oil with onion and tomato until the gravy turns dark and clings to the meat. Bengali Sunday cooking, the kind that takes three hours and leaves the kitchen smelling of warm spice. Eaten with luchi or rice.

Kosha mangsho (literally browned meat in Bengali) is the dry-style goat curry that anchors a Bengali Sunday lunch from Kolkata to Dhaka. The kosha part of the name refers to the technique of slowly browning the meat hard in oil before any liquid joins the pot; the deep mahogany colour that the dish takes on is the visual signature of a properly executed kosha.

Mustard oil heated to smoking point is the medium that pulls this into the Bengali register rather than the broader North Indian goat-curry repertoire. The pungency mellows under the heat but leaves a distinct, nutty depth that ghee or vegetable oil can't reproduce. Goat shoulder, with its high collagen and connective tissue, transforms over the three-hour cook from chewy and tough into silky and tender.

Shahi garam masala is the upgrade on a standard garam blend, leaning heavier on green cardamom, mace and rose petals for a more aromatic, less hot finish. Yoghurt in the marinade tenderises the meat overnight; pureed onion forms the base of the gravy. Eat with luchi (the Bengali puffed-puri version of wheat bread) or steamed basmati. A glass of cold lassi alongside; the kind of Sunday lunch that ends in a long nap.