Heat a lug of oil in a large pan.
Keep the heat on medium.
Add the mustard seeds and wait for them to pop.
Add the curry leaves and red chilies, stir and then add the onions.
Cook the onions until soft and add the ginger and garlic. Cook for a few seconds as you don’t want the garlic to burn.
Add the tomatoes, salt, turmeric, red chili powder. Cook for about a minute on low heat.
Add a little water, about 1/2 a cup, and bring to a boil.
Add the fish and simmer for about 20 minutes, or until the fish is cooked.
Finally, add the coconut and garnish with coriander.
Best served with steamed rice.