Marinate the fish with a pinch of salt, turmeric powder and red chilli powder for 10-15 minutes.
Heat oil in a pan / kadai and temper with mustard seeds. After it stops spluttering add the cumin seeds and fenugreek seeds. Saute for a few seconds and then add the garlic. Saute for a few seconds more.
Add the onion, green chilies and curry leaves. Stir fry till light brown.
Add the ginger-garlic paste and stir for few seconds more.
Now add the tomatoes and cook till it is completely mashed.
Add all the dry spices & toss well.
Add in the tamarind water & bring it to a boil.
Gently drop in the marinated fish and simmer, covered for 5-6 minutes.
When done, switch off the flame and garnish with coriander leaves.
Serve with plain steamed rice.
