1. Make sauce: Whisk tamarind concentrate into lime juice in a small bowl until dissolved. Stir in remaining sauce ingredients and chill, covered.
2. Prepare shrimp: Coarsely chop coconut and transfer half to a shallow soup bowl or pie plate.
3. Whisk together flour, beer, baking soda, salt, cayenne, and egg in a small bowl until smooth.
4. Heat oil in a 4- to 6-quart deep heavy pot over moderately high heat until it registers 350 degrees F on thermometer.
5. While oil is heating, coat shrimp: Hold 1 shrimp by tail and dip into batter, letting excess drip off, then dredge in coconut, coating completely and pressing gently to help adhere. Transfer to a plate and coat remaining shrimp in same manner, adding remaining coconut to bowl as needed.
6. Fry shrimp in oil in batches of 8, turning once, until golden, about 1 minute. Transfer with a slotted spoon to paper towels to drain and season lightly with salt. Skim any coconut from oil and return oil to 350 degrees F between batches.
7. Serve shrimp with sauce.

Yield: 8 servings