How to Make It
Make 4 (3-inch-long) parallel cuts on each side of snapper, cutting down almost to the bone. Place fish in a 13- x 9-inch baking dish; set aside.
Combine lime juice, ginger, garlic, chiles, and black pepper in a blender. Process until smooth, about 45 seconds. Coat fish with chile marinade, rubbing into slits and cavity. Cover and chill at least 1 hour or up to 2 hours.
Meanwhile, preheat grill to medium-high (400°F to 450°F). Combine coconut milk, tamarind concentrate, tomato paste, turmeric, cilantro, and 1 teaspoon salt in a small saucepan. Bring to a boil over medium-high. Reduce heat to medium-low, and simmer, stirring occasionally, until flavors meld, about 10 minutes. Reserve 1/4 cup tamarind sauce for plating.
Using paper towels, wipe excess chile marinade from fish. Sprinkle fish with remaining 2 teaspoons salt, rubbing into slits and cavity. Place fish in a metal grilling basket coated with oil. Place grilling basket on grill grate, and grill, covered, basting fish occasionally with remaining tamarind sauce (about 2/3 cup), until flesh flakes with a fork, 18 to 24 minutes, flipping halfway through grill time. Carefully remove fish from grilling basket, and transfer to a platter. Pour reserved 1/4 cup tamarind sauce over fish, and serve with coconut rice.