Begin by preparing your steaming setup. If using banana leaves, cut them into squares (about 20 cm x 20 cm) and fold them into small bowls to hold the fish mixture. Alternatively, use small ramekins. Ensure the steaming water is ready to go, bringing it to a gentle simmer.

In a large bowl, mix the red curry paste and coconut milk until smooth. Make sure the curry paste is well incorporated into the coconut milk to create a rich base for your fish custard.

Add the finely chopped fish fillets to the curry mixture. Stir gently to coat the fish evenly with the curry-coconut mixture, ensuring the fish pieces remain intact for texture.

In a separate bowl, whisk the eggs, fish sauce, and palm sugar together until well combined. Gradually fold this egg mixture into the fish and curry mixture, ensuring an even consistency.

Add the thinly sliced kaffir lime leaves and Thai basil leaves into the mixture. These will add an aromatic and fresh element to the dish. Stir gently to avoid breaking up the fish.

Spoon the fish mixture into your banana leaf bowls or ramekins, filling them about three-quarters full. Ensure the mixture is evenly distributed to allow for proper steaming.

Place the filled banana leaf bowls or ramekins into your steamer. Steam the fish custard over medium heat for 20-25 minutes, or until the custard is set and the fish is cooked through. Avoid opening the lid during steaming to maintain a consistent temperature.

Once the custard is fully cooked, remove the bowls from the steamer. Garnish with thinly sliced red chili and fresh cilantro. Serve immediately, pairing with jasmine rice or as a standalone dish.