Rinse and drain 1 cup of sweet rice. Place rice in a heatproof bowl and add 1 cup of water to cover the rice. Make sure rice is fully submerged in the water. Place the bowl on top of the trivet into the Instant Pot [see note].
High-Pressure cook for 15 minutes and natural release.
Combine 1 can of coconut milk, 1/2 cup sugar, and 1/8 teaspoon of salt into a pot on the stovetop. Bring ingredients to a slight boil just to dissolve the sugar.
Pour half of the coconut mixture into the cooked sweet rice and stir well. Allow to soak and cool for 10 minutes.
In a small bowl, combine 1 tablespoon cornstarch and 1 tablespoon of cold water to create a cornstarch slurry. If you omit this step, the sauce will not be as thick or you can try using coconut cream instead of coconut milk for a thicker, richer sauce. Add this slurry to the other half of the coconut mixture to get a thicker sauce.
Peel and slice the mango. Arrange mango on top of sticky rice and add additional coconut sauce. Sprink with sesame seeds and enjoy!
Notes
* For the rice to water ratio – 1:1 seems to be sufficient for most [1 cup sweet rice, 1 cup water]. Depends on how you like the texture of your rice, if you prefer a softer texture, use 1 and 1/4 cup of water.