Assemble and cook these parcels a day ahead. Cool and chill until you're ready to serve. Order candlenuts from ImportFood.com, or look for them in Southeast Asian markets. Always cook the nuts before eating, as they're toxic if eaten raw. You can substitute 2 teaspoons grated lime rind for the Kaffir lime leaves. The creamy layer that forms on top of full-fat canned coconut milk adds a rich flavor to the dish. Be sure not to shake the can so the cream stays separated, and use only the thick top layer. Look for banana leaves at Asian or Latin markets (fresh or frozen) or order them from GroceryThai.com.
1 (2-inch) piece fresh galangal, peeled and coarsely chopped
1 (2-inch) piece fresh turmeric, peeled and coarsely chopped
15 shallots, peeled and coarsely chopped (about 1 pound)
1 teaspoon belacan (Malaysian shrimp paste) or 2 teaspoons fish sauce
2 tablespoons coriander seeds
2 tablespoons canola oil
1/2 cup thick regular coconut milk
1/2 cup light coconut milk
1 large egg, lightly beaten
1 pound Spanish or other mackerel fillet, skinned
1/4 cup superfine sugar (such as castor sugar)
1 teaspoon salt
8 Kaffir lime leaves, stemmed and cut into thin strips
18 banana leaves, cut into 6-inch squares
How to Make It
Place chiles in a medium bowl; cover with boiling water. Let stand for 30 minutes or until tender, and drain. Combine chiles, lemongrass, and next 3 ingredients (through turmeric) in a food processor, and process until finely ground. Add shallots and belacan; process until ground.
Heat a large skillet over medium heat. Add coriander seeds to pan; cook 1 minute or until toasted, shaking pan occasionally. Add seeds to chile mixture; process until ground.
Increase heat to medium-high. Add oil to pan, and swirl to coat. Add chile mixture to pan. Stir-fry for 5 minutes or until fragrant. Combine regular and light coconut milks, stirring with a whisk. Add coconut mixture to spice mixture, stirring to combine, and bring to a boil. Remove from heat. Cool for 15 minutes; stir in egg.
Place fish in food processor, and process until finely ground. Combine spice mixture, fish, sugar, 1 teaspoon salt, and lime leaves in a large bowl. Divide mixture into 18 equal portions (about 3 1/2 tablespoons each).
Preheat grill to medium-high heat.
Working with 1 banana leaf at a time, place leaf on grill. Grill 1 minute or until leaf color brightens and texture softens; remove leaf from grill. Spoon 1 portion fish mixture into center of leaf, shaping mixture into a 2 x 3-inch rectangle, and fold sides of banana leaf over fish mixture. Secure leaf with wooden picks. Repeat procedure with remaining banana leaves and fish mixture to yield 18 parcels.
Arrange parcels on grill rack, and grill for 3 minutes on each side or until desired degree of doneness. Chill at least 1 hour before serving.