To make Masala grind the til, dhania, jeera, mustard, khus khus, 1 tbsp grated coconut, chili powder, haldi garlic and 1 onion to a fine paste.
Extract 2 cups milk from the grated coconut. Extract the pulp from the tamarind soaked in 1 cup of water.
Heat oil and add the 1 sliced onion and fry till crisp. Put in the masala paste and fry till the oil separates.
Now add the fish pieces and fry a little. Pour in the coconut milk and add salt to taste along with the curry leaves.
Gently simmer till nearly done. Lastly add the tamarind water and again simmer a little.
Serve machhi ka salan hot.