Ingredients:

I used packaged frozen cleaned Salted Mackerel so i didn't need to clean it,but if you are using uncleaned fish , clean it thoroughly to remove excess salt and sand if any.

Salted Mackerel / Any Salted Fish - 2 fillet cut into bite size pieces.
Tamarind - 1 tsp(if u have mango which gives enough tart no need to add Tamarind)
Salt
Green Chilly - 4 slit
Raw Green Mango - 1 cut lengthwise
Curry leaf - 1 sprig
Small Pearl onion - 2 cut in quarters / Regular Onion - 1/2 of small size



To grind:


Coconut - 1 cup
Chilly pd - 1 1/2 teaspoon
Turmeric - 1 tsp
Jeera - 1 tsp
Small Pearl onion - 2 / Regular Onion - 1/2 of small size onions 
Curry leaf - 1/2 sprig


Method:

1.Grind all Ingredients in "to grind" list to a fine paste.

2.Pour in a ceramic/ clay pan(traditionally fish is cooked in these kinds of pan,if u don't have go with regular pan).Add Oil and saute Small Onions ,curry leaf and 2 Green Chillies .
3.Then add Drumstick and saute it a bit and then add mango along with salt.Add few more green chillies if you prefer.

4.Add grind ingredients.Add Some More curry leaf for garnishing.And let it come to boil,cover and cook till the drumstick is cooked enough.
5.Now taste it and add salt and tamarind paste if the mango is not sour enough to give gravy enough tanginess.
6.Then add fish and give a swirl for the gravy to cover the fish,then lower the flame to very low settings and cover and cook for 20 min.Garnish with some more curry leaf if you prefer.

7.Now switch off flame and let it sit for 20 min before serving.
8.Then serve with hot white rice.