Grilled Shrimp with Tamarind Sauce

Ingredients

 * 1½ lb jumbo (8 to 12 per lb) shrimp
 * 3 teaspoons sea salt dissolved in 1½ cups water

Tamarind sauce

 * 1 tablespoon tamarind from a pliable block
 * ⅓ cup water
 * 1 tablespoon peanut oil
 * 1 tablespoon chopped cleaned fresh cilantro roots and/or stems, pounded to a paste
 * 1 tablespoon minced garlic
 * 1 tablespoon sriracha or other Asian hot chile sauce
 * 1½ tablespoons palm sugar, or to taste
 * 1 tablespoon Asian fish sauce (preferably Thai naam pla), or to taste

Garnish

 * 2 fresh serrano or jalapeño chiles, seeded, halved lengthwise, and finely cut crosswise
 * fresh cilantro sprigs

Directions

 * 1) Prepare grill for cooking.
 * 2) Soak shrimp (still in shells) in salt water 5 minutes, then rinse well in a colander.

Tamarind sauce

 * 1) Place tamarind in a bowl with water and rub with your fingers to dissolve pulp.
 * 2) Pour through a strainer into a bowl, pressing hard on solids, and discard solids.
 * 3) Heat oil in a small heavy saucepan over moderate heat until hot but not smoking, then cook cilantro paste and garlic, stirring, until fragrant.
 * 4) Stir in hot sauce, 3 tablespoons tamarind juice, palm sugar, and fish sauce.
 * 5) Simmer until thickened to consistency of light syrup, about 3 minutes.

Grill shrimp

 * 1) Snip shells of shrimp with scissors down center of back, from wide end to second-to-last tail section.
 * 2) Butterfly shrimp in their shells, making a deep incision along length of back where shells are cut, and devein.
 * 3) 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, grill shrimp in a hot well-seasoned ridged grill pan over moderate heat)
 * 4) Spoon tamarind sauce over shrimp (still in shells) in a serving dish.