Wash the Thai sticky rice and then soak for at least 2 hours or overnight.
Drain and spread sticky rice on a wild plate layered with bamboo leaves or banana leaves (for adding some aroma, but you can use cloth too).
Set up the steamer, and steam the sticky rice firstly for around 15 minutes until the sticky rice is almost done.
During the first steaming, heat up coconut milk in a small pot. Add sugar and salt over slow fire. Stir slowly until the sugar is completely dissolved. Take 1/4 cup out for serving.
Pour the 3/4 cup of the coconut milk along to sticky rice and continue steaming for around 15 minutes over medium fire.
Cool down and transfer to serving plate. Pour the left 1/4 coconut milk on top and lay the mango cubes.
You can also to decorate with some other colors like roasted black sesame seeds and peppermint leaves.
Notes
This recipe is adapted here where a microwave version is also introduced. Choose your favorite method.