Put turmeric and salt to the shrimp and mix well. Set aside for 10 minutes. In a blender place the grated coconut, red chilies, coriander seeds, cumin seeds, fenugreek seeds & tamarind and purée with coconut liquid or water. Heat oil in a large pan and add the mustard seeds. When it starts to pop add asafetida, ginger, garlic & onion and fry until the onions are golden. Then add the puréed mixture and yogurt and cook for 5 minutes. Add shrimp and mix well. Simmer and cook uncovered for 15 minutes or until the shrimp is cooked. Garnish with cilantro leaves and serve hot with rice