Thoroughly rinse 1 cup of sticky rice under cool water until the water runs clear. Soak in water for at least 1 hour or overnight.

Drain the rice and transfer it to a heatproof bowl. Prepare a steamer system with boiling water and place the bowl inside. Steam for 20-25 minutes until tender and sticky.

In a medium saucepan, combine 1 cup of coconut milk, ¼ cup of sugar, and a pinch of salt. Heat over medium-low until the sugar dissolves without boiling.

If a thicker sauce is preferred, mix 1 tablespoon of cornstarch with 2-3 tablespoons of cold water to create a slurry and add to the saucepan, whisking continuously for 2-3 minutes.

Once the rice is steamed, pour 1 cup of the coconut sauce over the warm rice and gently stir to combine. Let it sit for a few minutes to absorb the flavor.

Scoop portions of the coconut-infused sticky rice onto a plate, serve with sliced mangoes and drizzle with remaining coconut sauce. Sprinkle with toasted sesame seeds if desired.