West Bengali lamb curry (khela kalia)

Method

1. Put the meat in a glass or ceramic bowl with the yogurt and mustard oil, if using. Stir to coat, then set aside to marinate for 30 minutes.
2. Meanwhile, briefly grind the rustic garam masala spices together in a spice or coffee grinder.
3. Pound the cumin seeds and green chillies together in a pestle and mortar to make a coarse paste.
4. Heat the vegetable oil in a large, wide heavy-based casserole (one with a lid). Add the potatoes and gently fry for 3-5 minutes until coloured on the outside. Transfer to a plate and set aside.
5. Add the bay leaves and black cardamom pods to the pan in the same oil and let them sizzle for 30 seconds, then add the chopped onions and fry for 8-10 minutes until they start changing colour.
6. Add the ginger-garlic and cumin-chilli pastes, then fry for 3-5 minutes more. When you see the oil start to separate around the onions, add the ground coriander and turmeric, the chilli powder and half the garam masala. Continue to cook over a low heat, stirring continuously to make sure the spices don’t burn.
7. Once the oil starts to separate again, add the marinated meat to the pan with the salt. Slightly increase the heat, then continue to ‘bhunno’ (fry to heat the spices sufficiently so their oils are released) for about 15-20 minutes, until the meat appears brown at the edges and the juices have evaporated.
8. Add the fried potatoes, remaining garam masala and the ghee to the pan and stir to combine. Add 1 litre water, then reduce the heat to a gentle simmer, cover and cook until the meat is tender and the potatoes have cooked through (about 1½ hours). Uncover the casserole and simmer for 15-30 minutes more until the sauce is thick and rich.
9. Taste and adjust the seasoning, then serve with vegetable pilau, garnished with coriander.