Ingredients

• 1 small coconut or 1 cup thawed frozen grated coconut
• 2 tablespoons brown mustard seeds
• 7 small fresh Thai chiles (2 to 3 inches; preferably green), 6 slit lengthwise on one side(not all the way through)
• 3 tablespoons water
• 1 lb large shrimp in shell (21 to 25 per pound), peeled, leaving tail and first segment of shell intact, and deveined
• 1 teaspoon ground turmeric
• 1 teaspoon salt
• 3 tablespoons vegetable oil
• Special equipment: an electric coffee/spice grinder; a mortar and pestle (optional); a wok

Instructions

1. Put oven rack in middle position and preheat oven to 400°F.
2. If using whole coconut, pierce 2 softest eyes of coconut with a small screwdriver or a metal skewer, then drain and discard liquid. Bake whole coconut 15 minutes. Break shell with a hammer and remove flesh, levering it out carefully with screwdriver or point of a strong knife. Finely shred enough coconut to measure 1 cup using the 1/8-inch-wide holes of a box grater.
3. Finely grind mustard seeds with a pinch of salt in grinder. Finely chop whole chile (without slit) and mash in mortar with pestle along with ground mustard seeds and a pinch of salt until chile is finely ground. Add 1 tablespoon water. Mix to a paste. (Alternatively, very finely chop chile, then stir with mustard seeds and water to form a paste.)
4. Toss shrimp with turmeric and salt.
5. Heat oil in wok over moderately high heat until hot but not smoking. Sauté shrimp, stirring, until it just turns pink, 2 to 3 minutes. Add grated coconut, mustard paste, remaining 6 chiles, and remaining 2 tablespoons water. Sauté, stirring, until water is absorbed and shrimp are well coated, about 2 minutes more.