Toss the shrimp with the turmeric, 2 teaspoons of the chile powder and salt.
Heat oil in a large skillet. Add shrimp and flash fry them for a few minutes, just until they get a little color. Remove and set aside.
Add the fenugreek, curry leaves and onion to the pan. Saute until the onions are softened. Add ginger and garlic and fry for 1 minute. Add the rest of the chile and the curry powder. Fry for 1 more minute.
Add coconut milk and salt. Bring to a boil. Reduce to a simmer and cook for 5 minutes.
Add tamarind and mix well.
Return shrimp to pan and cook for a few minutes until cooked through, 1-2 minutes.