Put turmeric and salt to the shrimp and mix well. Set aside for 10 minutes. In a blender place the grated coconut, red chilies, peppercorns, coriander seeds, cumin seeds, mustard seeds, ginger, garlic, onion & tamarind and purée with coconut liquid or water.
Heat oil in a large pan and fry the puréed mixture over medium heat for 10 minutes with constant stirring. Add shrimp and curry leaves and mix well. Simmer and cook for 15 minutes or until the shrimp is cooked. Garnish with cilantro leaves and serve hot with rice.