Put your block of santen into a liter of water and heat slowly while you let the pandan leaves infuse. Add 1/2 tsp of salt into it as well.
Take of the heat (don't let it boil) and leave to cool. Toss the pandan leaves.
Put rice flour, tapioca flour and sugar in a bowl, mix this well and add to your santen mix. Stir until it is smooth and any lumps are gone. Divide into two separate quantities. Add the pandan paste to one half. Leave the other half white.
Prepare a steamer and check that your cake tins (well greased) fit into the steamer. Bring water to the boil and start by adding a small layer of the green mix into the tin. Leave to steam for about 6 minutes and then follow with the next layer in a different color. Keep doing that until your mould is full or you run out of batter.