In a separate wok, add oil and heat it.
Add green chillies, add sliced onions and cook the onions until they turn soft.
Add salt as per taste, ginger garlic paste and saute until raw smell of ginger garlic paste disappears.
Add chopped tomatoes, mix well.
Add red chilli powder, roasted coriander seeds powder, mix well and cook the masala until oil leaves the sides.
Add coconut powder, mix well and cook the gravy for few minutes.
Add the sauteed prawns into the masala gravy, mix carefully and cook for 4-5 minutes.
Add 1 cup water and stir well.
Add curry leaves, coriander leaves, mix well and cook the gravy on low flame for few minutes until oil appears at the sides.
Switch off the flame.
Serve the prawn curry masala with steamed rice.