Grilled Shrimp with Tamarind Sauce

Prepare grill for cooking.

Soak shrimp (still in shells) in salt water for 5 minutes, then rinse well in a colander.

To make the sauce, place tamarind in a bowl with water and rub with your fingers to dissolve pulp. Pour through a sieve into a bowl, pressing hard on the solids. Discard solids.

Heat oil in a small heavy saucepan over moderate heat until hot but not smoking, then cook cilantro paste and garlic, stirring, until fragrant. Stir in hot sauce, 3 tablespoons tamarind juice, palm sugar, and fish sauce. Simmer until thickened to the consistency of light syrup, about 3 minutes.

To prepare the shrimp, snip shells of shrimp with scissors down center of back, from the wide end to the second-to-last tail section. Butterfly shrimp in their shells, making a deep incision along the length of the back where shells are cut. Devein.

Grill shrimp on their sides on an oiled rack set 5 to 6 inches over glowing coals, until shells are pink and slightly charred and shrimp are just cooked through, 3 to 4 minutes on each side. (Alternatively, you can grill shrimp in a hot well-seasoned ridged grill pan over moderate heat.)

Spoon tamarind sauce over shrimp (still in shells) in a serving dish.