Marinate the fish pieces with a pinch of turmeric, salt and red chilly powder.
Heat oil in a pan or a kadai.
Add small onions, garlic, ginger and green chillies and saute, till they turn brown. Keep it aside.
Heat up the same pan.
Add red chilly powder, coriander powder, pepper powder, fenugreek, garam masala powder and turmeric powder and fry, till the raw smell leaves.
Grind both the mixtures together.
Heat oil in a pan or a kadai.
Add curry leaves and onions and saute, till the onions turn brown.
Add the ground masala and mix well for a minute.
Add tomatoes and salt and mix, till it becomes a paste.
Add the tamarind pulp and fish pieces.
:- If you prefer, fry the fish pieces lightly.
Add the coriander leaves.
Cover the pan and let it simmer, till the oil comes on top. It takes about 5 - 10 mins.