Kosha Mangsho Durga Puja Bengali Mutton

Method

1. 1

   Marinate the mutton: Combine mutton with yogurt, ginger paste, garlic paste, red chilli powder, turmeric and salt. Mix thoroughly so every piece is coated. Marinate for minimum 3 hours — overnight in the refrigerator gives visibly better results.

2. 2

   Heat mustard oil until smoking: Heat 4 tbsp mustard oil in a heavy pot — a thick-bottomed kadai or Dutch oven is ideal — until smoking. Reduce to medium-high. The hot mustard oil is essential for the depth of Kosha Mangsho.

3. 3

   Add whole spices: Add bay leaves, crushed cardamom, cloves and cinnamon. Sizzle 20 seconds.

4. 4

   Cook onions until very dark — the most important step: Add finely chopped onions. Cook on medium-high heat, stirring every 2 to 3 minutes, for 20 to 25 minutes until deeply, darkly caramelised — almost reddish-brown. This is much darker than most curries. Do not rush this step. The dark caramelised onion is the entire foundation of Kosha Mangsho.

5. 5

   Add the marinated mutton: Add the mutton with all its marinade. Increase to high heat. Cook stirring and turning the pieces for 10 to 12 minutes. The yogurt marinade will sizzle, splutter and cook away — let it reduce completely.

6. 6

   Add spice powders on low heat: Turn to low. Add red chilli powder, cumin powder and coriander powder. Stir for 3 minutes on low heat.

7. 7

   Add sugar: Add 1 tsp sugar. Stir — the sugar will caramelise slightly and add depth.

8. 8

   The koshano technique — cook without water: This is the defining technique of Kosha Mangsho. Cover the pot tightly. Cook on the lowest heat for 40 to 50 minutes, checking every 10 minutes. The mutton cooks in its own juices and the marinade — no water added. If it looks dry, add just 2 tbsp water.

9. 9

   Uncover and reduce: After 40 to 50 minutes the mutton should be fully tender. Uncover. Increase to medium. Cook 5 to 8 minutes until the gravy reduces to an almost-dry coating on the meat. The oil will separate and pool — this is correct.

10. 10

    Add garam masala and serve: Add garam masala. Stir gently. Serve with luchi (fried bread) or steamed rice.

11. 11

    Note: Kosha Mangsho (kosha = dry-fried/caramelised, mangsho = mutton) is one of the most important dishes of Bengali cooking — made for Durga Puja, weddings, and every significant family occasion. The kosha technique of cooking meat in its own juices without added water is what produces the characteristic thick, almost-dry, intensely flavoured coating. Bengalis judge a cook's skill by their kosha mangsho.