Heat coconut oil in a pan and add in the mustard seeds and methi/ fenugreek seeds. Let the mustard seeds splutter. Add in the ginger, green chillies and and curry leaves. Sautee briefly for 10 seconds.
Add in the shallots and fry till they are soft.
Take a small cup and add in the masala powders to the cup. Turmeric powder, red chilli powder and coriander powder. Add ¼ cup of water and make a paste.
Add the paste, tomato and the salt to the pan. Sautee for a couple of minutes. Add in the mangoes and a cup of water. Let it come to a boil.
Grind the coconut with about half a cup of water to a smooth fine paste. Add it to the pan.
Add in drumsticks and let the curry simmer for 10-12 minutes on medium flame. Add fish pieces and simmer till cooked. About 5 minutes or so. Don’t overcook the fish.
Serve hot immediately but I like the best after it has sat for a day or atleast a couple of hours