Start by roasting coconut till golden brown in a kadai. Remove it to a blender and make it into a fine puree.
Now in the same kadai. add in all the ingredients given for cooking fish. Add in fish and cover and cook for 5 mins till the fish is half cooked. Remove it to bowl.
Now in the same kadai. Add in oil and fry ginger, garlic and curry leaves.
Add in onions, sprinkle some salt and saute for 5 mins till it turns light golden.
Add in tomatoes and cook for further 5 mins till it turns mushy.
Now add in chilli, coriander and turmeric powder. Mix well.
Add in tamarind pulp, coconut paste and saute for 7 to 8 mins till it is well mixed and oil separates.
Add in the cooked fish along with any liquid. Mix well.
Cover and simmer again for 5 to 7 mins or till oil floats.