Prepare the masala by heating the oil, and add all the ingredients into the hot oil. Cook for a few minutes till aromatic. Allow to cool.
Add little water and grind to a smooth paste.
To prepare the curry, heat oil in a saucepan. Saute the shallots and green chillies till wilted.
Add in the tomatoes and cook till wilted. Sprinkle water if it sticks to the pan.
Squeeze the tamarind well and discard the waste. Pour the water and bring to boil.
Add the fish and salt and cook on low flame till half done.
At this stage, add the paste and cook till the fish is well done. Adjust seasoning.
Serve the curry hot with rice.