Preheat oven to 200C/180C fan/gas 6. Mix the tamarind paste with the lime, sugar, salt, chilli powder, turmeric, garlic and ginger. Add enough water – you won’t need much – to make sufficient marinade to coat the four pieces of fish. Turn the salmon over in the marinade, making sure it gets well coated, cover and put in the fridge for 1 hr (or 30 mins is fine if you’re in a rush).
Heat the oil in a large frying pan and add the chillies. Fry over a medium heat for 30-40 secs, then add the salmon fillets. Brown the fillets on each side (including the skin), then transfer them to a roasting tin. Spoon some of the chilli oil from the pan over them. Bake in the oven for 12 mins, or until the fish is cooked right through to the centre (check with the tip of a knife). Serve with rice, lime wedges and an Indian chutney.