Ingredients:

• 60ml vegetable oil
• 1 tbsp yellow mustard seeds
• 1 large onion, finely chopped
• 15g / 3 cloves garlic, finely crushed
• 30 fresh curry leaves
• 2 tsp Kashmiri chilli powder
• 2 tsp ground coriander
• 2 tsp turmeric
• 400g can of chopped tomatoes
• 100ml Tamarind liquid (see ingredients and method below)
• 2 green chillies, each sliced lengthways into 6 pieces, with seeds
• 1 tsp salt
• 700g snapper fillets, cut into 5cm chunks
• Boiled basmati rice, to serve

For the tamarind liquid:

• 60g tamarind pulp
• 120ml just-boiled water

Method:

First, make the tamarind liquid.

1. Take the tamarind pulp and put it in a bowl with the water.
2. Leave to soak for 15 minutes, then work the paste with your fingers until it has broken down and the seeds have been released.
3. Strain the slightly syrupy mixture through a fine sieve, rubbing it well against the sides of the sieve to extract as much of the liquid as possible.
4. Discard the fibrous material and seeds left behind.
5. Heat the oil in a heavy-based saucepan or karahi over a medium heat.
6. When hot, add the mustard seeds and fry for 30 seconds, then stir in the onion and garlic and fry gently for about 10 minutes until softened and lightly golden.
7. Add the curry leaves, chilli powder, coriander and turmeric and fry for 2 minutes.
8. Stir in the tomatoes, tamarind liquid, green chillies and salt and simmer for about 10 minutes until rich and reduced. 
9. Add the fish, cook for a further 5 minutes or until just cooked through.
10. serve with plain rice.