Preparation:

1. To make the burnt coconut shell water : charcoal-grill 2-3 mature coconut shells until burnt. Pound the burnt shells roughly. Put the pounded shell into 2-3 cups of water. Let it stand until settled. The water should become dark and black. Reserve 4 tablespoons of the black colour water for colouring.
2. Dissolve rice flour and tapioca flour in coconut milk, water and the burnt coconut shell water (black colouring water). Add palm sugar. Stir until all mixed well and filter.
3. Heat the mixture from step 2 over low heat. Using a wooden spatula to stir until it forms and becomes sticky. The right texture should be very sticky that it does not drip from the wooden spatula when lifted.
4. Place the sticky mixture in a square plate. Let it cool.
5. When serving, cut into small rectangular shape. Sprinkle with grated coconut and salt.

Note : The burnt coconut shell is a typical Thai natural food colouring for the black colour.