Prepare all ingredients before starting to cook.
Pour 1/2 cup boiling water onto kokum (or tamarind) to soak for 10 min at least. Mash with fingers and remove seeds.
Heat the coconut oil in a pan & add one at a time (sauté as you go) ginger, garlic, green chilli and curry leaves. and then onions. Saute till light brown in colour.
Add onions. Saute till light brown in colour.
Add turmeric powder, chilly powder, coriander powder and Sauté for a moment and do not allow the powders to get burnt.
Add the fish cubes and kokum with the water, salt and extra 1/2 cup water.
Simmer the fish until cooked and add more water if needed.
Remove from heat and add coconut milk.
Mix well.
For tempering:
Heat the oil in a small pan. Add mustard seeds and saute until they pop. Add sliced shallots & curry leaves. Sauté it till it gets a nice brown colour and add the fennel powder and suate briefly.
Garnish the hot Meen Mappas with this tempering and serve hot with Kerala paratha or rice.