- Add 2 tbsp water into red food colouring and mix well. In a bowl, add red food colouring mixture with water chestnuts, mixing well to ensure each cube of water chestnuts are coated with colouring. Allow to sit for a while until they are evenly coloured.
- Stir in half the tapioca flour and combine well until each piece of water chestnut is well coated. Scoop them out and lightly spray with water before coating them with the other half of tapioca flour. Place coated water chestnuts into a colander and lightly shake off excess flour.
- Bring a pot of water to a boil. Carefully ladle in coated water chestnuts and cook for 1 min. Remove them once they float to the surface and transfer them to a bowl of cold, iced water.
- In a small saucepan, pour in water, sugar and coconut milk and heat through over medium flame until sugar dissolves. Remove from heat and allow the syrup to cool down.
- To serve, pour some syrup into a serving cup or bowl. Add crushed ice and cooked water chestnuts.