Heat oil in a kadai, add in all roasting ingredients except coconut and saute for a min. Add in coconut and roast till it gets golden and well roasted. Take them in a bowl and let it cool for 5 mins. Now take the roasted mix in a blender and make it into a smooth puree by adding some water.
Now take drumstick, raw mango, brinjal and curry leaves in the same kadai. Add in some water, coconut masala and salt. Cover this and cook for 10 mins till the veggies is cooked.
Now add in tamarind pulp and mix well. Boil this for 5 more mins.
Add in fish pieces and cook for 7 to 10 mins till the fish is cooked.