Peel and finely chop the ginger and onions. Chop the tomatoes. Heat 3 tablespoons of oil in a frying pan, and when it's almost smoking, add half the mustard seeds, the fenugreek, ginger and half the curry leaves. Stir-fry for a few seconds, then add the onion and cook over a medium heat until it's dark golden. Add the chilli powder, coriander and turmeric, and stir for a few seconds.
Add the tomato and tamarind pulp. Simmer until slightly reduced and you can start to see oil separating from the sauce. Add a few tablespoons of
water to get the sauce back to the consistency it was before, season with sea salt and add the prawns.Simmer until the prawns are cooked and the sauce is quite dry. Add the coconut milk, bring back to boil and turn the heat down to low. In another pan, heat 1 tablespoon of oil, the chillies and remaining mustard seeds and curry leaves. Fry for 10 seconds or so, then tip into the curry. Serve with steamed rice.
Serves 2 – 3