1. 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.
2. 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.
3. 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.
4. 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).
5. Preheat grill to medium-high heat.
6. 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.
7. 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.