keralastyle spicy fish curry

This recipe is a kerala style spicy fish curry that is best prepared with Sardine, coconut oil and shallots on a clay pot. It pairs well with tapioca and rice.
To prepare ginger/garlic paste, grind some fresh ginger/garlic in a grinder. This can be stored in the freezer to be used when required.

Ingredients

Sardine (mathi fish), 350 g
Lemon juice, from 1 lemon -or- Vinegar, 2 tbs
Malabar tamarind (kudam puli), 3 pieces
Ginger paste ½ tbs
Garlic paste ½ tbs
Chili powder, 2 tbs (1 ½ tbs kashmiri and ½ tbs regular) 
Turmeric powder, ½ tsp
Pepper powder, ½ tsp
Coconut oil, 2tbs +1 tbs
Mustard seeds, 1 tsp
Fenugreek seeds, ½ tsp
Onion (finely chopped), 1 no. (medium) -or- shallots (finely chopped), ½ cup
Curry leaves, a few
Green chili (slit), 2 nos. 
Water, 2 cups
Salt, to taste
Coriander leaves, a few

Preparation:

Cooking time 30 minutes
Clean sardines with salt and lemon juice or vinegar. 
Wash the Malabar tamarind (kudam puli) and soak for ten minutes.
Mix the ginger paste, garlic paste and spices with one tablespoon water and set aside
If you do not have ginger/garlic paste, you can crush some in a mortar and pestle.
Heat oil in a clay pot and add mustard and fenugreek seeds. Once the mustard seeds pop, add onion and curry leaves, and sauté by adding salt until the onion turns soft and light brown. Add the spice paste and sauté until the oil separates.
Add two cups of water and bring to boil.
Add salt (if required) and kudam puli along with water and mix with gravy; then boil for five minutes.
Add cleaned fish and cook covered over a medium flame.
Stir from time to time very slowly.
Once the gravy is thickened and fish is well cooked, add one tablespoon of coconut oil and twirl the pan (mixing can cause the fish to crumble).
Switch off the flame, sprinkle coriander leaves and curry leaves.
Set aside to cool. Serve after one hour.
Enjoy this fish curry with kappa or rice. Please share and comment! Thank you :)