Soak the rice in a large bowl of water for 89 hours then drain and rinse the rice under running tap water.
Line a steamer with a piece of muslin and add 23 blades of screwpine leaves. Spread the rice over and steam for 3040 minutes. Check and taste the rice after 20 minutes to make sure that the consistency is right. Sprinkle a little water over the rice to help it along. Remove and leave aside to cool.
Heat the coconut milk in a saucepan. Add salt, sugar and corn flour. Remove the saucepan from the heat the moment it starts to thicken.
Serve the glutinous rice with mango slices and a generous serving of sweet coconut cream.