Heat the oil in a large frying pan. Fry onion until brown.
Add ginger and garlic.
Season with turmeric powder and pour in the coconut milk. Cook over low heat and then add salt and fish. Cook until fish is tender, 5 to 10 minutes. Add tomato and coriander leaves just before serving.
I added a finely chopped small red chilli with the 5 teaspoons of garlic and ginger, and a half cup of fresh grated coconut. Extra delicious, and I'll be doing variations of this quite regularly. - 18 Apr 2014