Prepare the Banana Leaves: Remove soaked banana leaves from water and pat dry with a paper towel. If your leaves are large, you may need to trim them into squares approximately 8x8 inches. If they have tough veins, gently scrape them away with a knife for better flexibility.
Make the Sauce: In a small bowl, whisk together the coconut milk, tamarind paste, brown sugar, turmeric, chili flakes, and salt until smooth. Taste and adjust seasoning if needed; it should be tangy and slightly sweet.
Assemble the Packets: Lay one banana leaf square on your work surface. Place a portion of fish chunks in the center. Drizzle about 2-3 tablespoons of the sauce over the fish. Carefully fold the sides of the leaf up and over the fish, then roll tightly from the bottom to seal into a neat packet. Repeat with remaining leaves and ingredients.
Steam: Place the packets in a steamer basket over boiling water. Cover and steam for 15–20 minutes. The fish is done when it flakes easily with a fork and reaches an internal temperature of 145°F (63°C). Avoid over-steaming, which can make the fish tough.
Prepare the Egg Salad: While the fish steams, chop the hard-boiled eggs into small cubes. In a medium bowl, combine the chopped eggs, roasted peanuts, mayonnaise, lemon juice, and Dijon mustard. Season with salt and black pepper to taste. Mix gently until well combined but still chunky.
Serve: Carefully open each banana leaf packet at the table to release the aroma. Spoon some of the steaming coconut sauce from the bottom of the leaf over the fish. Serve immediately alongside a generous portion of the egg and peanut salad, garnished with fresh cilantro.
