Preheat the oven to 450 degrees F (230 degrees C/gas 8).
To make the banana leaves more pliable, hold for a few seconds over a gas flame. Leaving aside the fish and herb sticks, pound the rest of the ingredients in a pestle and mortar to make a thick paste and spoon a little onto each banana leaf. Place the fish on top and then spoon the rest of the paste on the top. Bringing the sides in and spiking it with a rosemary sprig or bay leaf stick to secure it. This will look lovely and it is natural, but I have been known to use a clothes peg or string to hold it all together. It won't be a perfect seal but this allows it to breath and steam, letting the flavors infuse, so gutsy and tasty. Put the parcels on a tray and bake for 15 minutes, then remove from the oven, and allow to rest for 5 minutes.
I serve the individual parcels on plates at the table and let my friends dissect them. When opened, the fragrant steam wafts up and smells fantastic. Serve with plain boiled rice to mop up the juices, that's all it has to be. End of story, done, lovely.