Step 1: In a medium bowl, combine the coconut milk, red curry paste, fish sauce, palm sugar, and broth, whisking until smooth—this ensures no lumps in the sauce.
Step 2: Heat the vegetable oil in a large skillet over medium heat (about 350°F) for 30 seconds until shimmering.
Step 3: Pour the coconut milk mixture into the skillet and bring it to a gentle simmer, stirring occasionally, which should take about 3-4 minutes.
Step 4: Add the fish cubes and kaffir lime leaves to the skillet, submerging them fully in the sauce.
Step 5: Reduce the heat to low, cover the skillet, and let it cook for 10 minutes until the fish is opaque and flakes easily with a fork—avoid overcooking to keep it tender.
Step 6: Stir in the beaten egg slowly, cooking for 2 more minutes until the sauce thickens slightly, which adds a rich, custard-like texture.
Step 7: While the curry simmers, prepare the banana leaves by briefly passing them over a gas flame for 10 seconds to make them pliable, or use parchment paper as a handy alternative.
Step 8: Spoon the curry into the center of each banana leaf square, folding the edges to form a tight packet to trap steam.
Step 9: Place the packets in a steamer basket over boiling water and steam for 10 minutes until heated through and fragrant.
Step 10: Carefully unwrap the packets and garnish with fresh cilantro and lime wedges before serving