1. Wash the prawns thoroughly under running water.
2. Drain & pat dry.
3. Sprinkle with salt and set aside for 1 hour,preferably in the refrigerator.
4. Grind with coconut, half the onion, garlic, turmeric powder and tamarind pulp to a smooth paste.
5. Heat oil in a pan and fried remaining chopped onions till light brown.
6. Add the masala paste and sauté for two to three minutes.
7. Add two cups of water and bring the mixture to a boil.
8. Add prawns and adjust seasoning.
9. Simmer for 5 minutes.
10. Serve hot.