Wet-grind all ingredients except for the oil, green chilly, onions and prawns. Keep the fine-ground paste aside. If fresh coconut is unavailable then use canned coconut milk to which turmeric, chilli, coriander powders, salt, hing and tamarind paste can be added. Also add pepper powder instead of the peppercorns.
Heal oil in a saucepan, saute the chopped onion and green chilly till the onion is lightly colored, but not browned. Add the peeled prawns and saute for 1 min on low fire. Add the coconut paste and add water to make the curry of a consistency such that it can be mixed with boiled rice to eat it. Heat the curry until it comes to boil but do not allow it to heavily boil as then the coconut milk splits and the curry is spoiled.
Eat with boiled rice, with fried fish and vegetables as sides.