Grind curry leaves,coriander leaves, onion(small onion) about 6 of them, pepper, ginger, cumin seeds with water and keep aside. Use little of each. In a pot, use nallayennai and season mustard, methi seeds and cumin seeds and curry leaves, fry them and then add tomatoes. Pour the ground matter and fry for a while for the raw onion smell to disappear.Make a thick extract of tamarind juice and add chilli powder, turmeric powder and salt. Pour this extract in the pot and cook on low fire. When the content is almost thick, add cut cleaned fish. and remove from fire when done.