Keralan sour fish curry with kokum

Not unlike tamarind, the Indian spice kokum has a sour bite; in this monkfish curry recipe it balances well with the heat of the chilli paste.

Ingredients

500g/1lb 2oz monkfish tail, cut into 12 pieces
½ tsp ground turmeric, plus extra for marinating
½ tsp salt
½ tsp fenugreek seeds
2 tbsp red chilli paste
400ml/14fl oz water
2 tbsp olive oil
½ tsp mustard seeds
10-12 curry leaves
2 medium onions, grated
1 tbsp finely sliced garlic
2 pieces kokum (fish tamarind), washed and left to soak in 50ml/2fl oz warm water
cooked basmati rice, to serve

Rinse the fish, pat dry and rub in a little turmeric and some of the salt. Set aside to marinate.
Dry-fry the fenugreek seeds for a few seconds in a small frying pan (be careful not to over-roast the seeds as this will make them bitter), then grind them using a spice grinder or pestle and mortar
Mix the fenugreek, chilli paste and half a teaspoon of turmeric together with 50ml/2fl oz of water, forming a paste.
Heat the oil in a deep, heavy-based frying pan. Add the mustard seeds, when they start popping after a few seconds (CAUTION: keep the pan well away from your face and eyes), add the curry leaves, onions and garlic and fry for 3-4 minutes, or until the onion is translucent.
Add the remaining salt and the fenugreek paste and fry for a further 3-4 minutes. Add the remaining water and bring to the boil, reduce the heat and simmer for 20 minutes.
Add the soaked kokum, plus its soaking water, and simmer for a further 10 minutes, or until the mixture thickens a little. Add the monkfish and simmer gently for another 10 minutes, or until the fish is cooked through.
Serve hot on a bed of rice.