[Malaysia] How to cook Red bean, coconut and grass jelly dessert drink

Ingredients
- 220 g (1 cup) red (adzuki) beans, soaked overnight in plenty of cold water
- 330 g (1½ cups) caster sugar
- 500 ml (2 cups) tinned coconut milk
- 250 ml (1 cup) milk (you can use coconut milk here as well for a richer taste)
- ¼-½ tsp salt
- 2 fresh or frozen pandan leaves, shredded lengthways and tied into a knot
- 270 g tinned grass jelly, cut into 1 cm cubes (see note)
- crushed ice, to serve