Heat the pandan leaf juice and fresh coconut water (2 1/2 cups/600 ml) with 1 cup (200 grams) sugar until the sugar dissolves, then let cool. Strain the mixture, then add the tapioca starch and rice flour and mix well.

Cook the mung beans until soft, then mash them. Stir in 1/3 cup (70 grams) sugar and cook until the mixture thickens slightly. Add the coconut milk, 1/3 cup (50 grams) tapioca starch, and vanilla, and mix until smooth.

Prepare a steamer and bring the water to a boil. Grease a cake pan and place it in the steamer. Pour a layer of the pandan batter into the pan, cover, and steam for 2–3 minutes until set. Add a layer of the mung bean mixture and steam again. Continue alternating layers until all the batter is used. Let the cake cool completely before removing it from the pan.