Bengali Lamb Kosha — Kosha Mangsho
Terrible photo, amazing curry with real depth of flavour
Servings 6 people
Ingredients
Lamb & marinade
- 1.2 kg lamb chump trimmed of the thick external fat
- 150 g full-fat Greek/natural yoghurt
- 25 g fresh ginger finely grated
- 5 cloves garlic finely grated/crushed
- 1 tsp turmeric
- 1½ tsp Kashmiri chilli powder
- 1½ tsp salt
- 1 tbsp mustard oil if you have it
For the kosha
- 3 large onions about 500–550 g, thinly sliced
- 3 tbsp mustard oil ideally; otherwise vegetable/rapeseed oil
- 1 tsp sugar
- 2 bay leaves
- 1 cinnamon stick about 5 cm
- 5 green cardamom pods lightly crushed
- 4 cloves
- 1 tsp cumin seeds
- 2 dried red chillies optional
- 20 g fresh ginger grated
- 4 cloves garlic crushed
- 1½ tsp ground cumin
- 2 tsp ground coriander
- 1 tsp Kashmiri chilli powder
- ½ tsp hot chilli powder optional
- 2 medium tomatoes finely chopped or 150 g tinned tomatoes
- 250 –400 ml hot water
- 1 tsp garam masala
- Salt
- ½ tsp sugar if needed at the end
Instructions
Marinade the Lamb
- Cut the lamb into large 4–5 cm chunks. Don’t cut it too small—you want substantial pieces after the long cook.
- Mix everything together thoroughly and refrigerate for 3–4 hours. Even 2 hours will make a difference.
- Take it out of the fridge about 30 minutes before cooking.
The important bit: build the dark base
- Heat the mustard oil in a heavy casserole until properly hot. If using mustard oil, let it just reach the point where it begins to smoke, then turn the heat down.
- Add the 1 tsp sugar and let it caramelise until deep amber. Don’t let it actually burn.
- Add the bay, cinnamon, cardamom, cloves, cumin seeds and dried chillies. Fry for about 30 seconds.
- Add all the onions and a pinch of salt.
- Now take your time: 20–30 minutes over medium/medium-low heat, stirring periodically, until they’re properly dark golden-brown. Don’t stop when they’re merely soft and translucent—the onion browning is fundamental to the finished curry.
- Add the ginger and garlic and cook another 2 minutes.
- Add cumin, coriander and chilli powder with a splash of water. Cook the spices for another 2–3 minutes, stirring, until the oil starts separating from the mixture.
- Add the tomatoes and cook for 8–10 minutes, until they’ve almost disappeared into the masala.
Kosha the lamb
- Now add the lamb along with all its yoghurt marinade.
- Turn the heat up to medium-high.
- Cook for 15–20 minutes, stirring and turning the meat frequently.
- This is the kosha/bhuno stage and it’s worth taking seriously. You’re effectively frying the lamb and its marinade into the onion-spice mixture. Initially it will release quite a lot of liquid; keep cooking until that has evaporated and the masala becomes thick, dark and glossy and starts clinging to the meat.
- You’ll see little beads of fat/oil beginning to appear around the edges.
- At that point you’ve built the flavour of the curry.
Slow cook
- Add 250 ml hot water and scrape everything from the bottom of the casserole.
- Bring just to a simmer, cover and put into a:
- 140°C fan / 160°C conventional oven
- for approximately 2–2½ hours.
- Check after about 90 minutes. Give it a stir and add another 50–150 ml water if it’s becoming too dry.
- Because your lamb is chump rather than tougher traditional mutton, start checking tenderness at about 1 hour 45 minutes. You want it completely tender but still holding together.
The final reduction
- This is what takes it from “nice lamb curry” to kosha.
- Once the lamb is tender, put the casserole back on the hob uncovered over medium-low heat.
- Cook for perhaps 10–20 minutes, stirring fairly regularly, until the sauce reduces dramatically.
- You’re looking for very little free liquid. The gravy should be dark brown-red, glossy and thick enough that it coats each piece of lamb.
Stir in:
- * 1 tsp garam masala
- * salt to taste