Preheat oven to 400 degrees. Combine the topping ingredients in a bowl. Place a fillet on each of the banana leaves and divide the topping evenly among them, spreading it over the top. Fold the banana leaves over to form a packet around each fillet and seal the edge of each packet with a small piece of aluminum foil, crimping it tightly. Place on a baking sheet and bake 25 to 30 minutes.