The first thing you should do before you cut the fish fillets into small pieces is to make sure that there no bones inside them.
After cutting the fish fillets into small pieces mix them together with the onion, nuts, chili powder, turmeric, lemon grass, mint, black pepper, sugar, coconut milk, coriander and salt in a food processor until they form a smooth mixture.
Before you can place any of the fish cake mixture on to a piece of banana leaf measuring 6 inches square they leaves need to be boiled in water for about a minute as this will help to soften them up and make them more pliable to use.
As soon as the banana leaves are ready place 2 tablespoons of the fish cake mixture on to each one and then fold the leaves over.
To keep the leaves securely in place pierce through the areas where they come together with a toothpick.
You should be doing this whilst the barbecue is heating up.
As soon as the barbecue has heated place the banana leaves with the fish cake mixture inside on to the barbecue and cook on a high heat for 5 minutes.
It is important that halfway through this time you turn the fish cakes over to ensure that they are cooked evenly.
Once the fish cakes are ready serve to your guests still encased in the banana leaves.