Grind, grated coconut, turmeric powder, tamarind, peppercorns, coriander and red chilies by adding 3/4th cup water.
In a kadai, add 1/4th cup water, prawns, chopped onion, radish and raw mango pieces. Add 2 tablespoon gravy to this. Let it cook for 10 minutes.
Then pour the gravy from mixer and stir. Add 1/2 cup water and simmer on a medium flame for 2 minutes.
Let it get cooked for another 10 minutes.
Switch of the gas.
Add salt to taste.
Remember that the prawns were marinated with salt. So add only 1/2 teaspoon salt first. Taste and add more if needed.