Rinse the glutinous rice under cold running water until the water runs clear. Soak it in water for at least 4 hours or overnight.

Drain the soaked rice and steam it in a cheesecloth-lined steamer basket over boiling water for about 20-30 minutes until translucent and tender.

While the rice is steaming, heat 1.5 cups of coconut milk in a saucepan over low heat. Add 0.5 cup of sugar and 0.25 teaspoon of salt, stirring gently until the sugar dissolves. Do not let it boil.

Once the rice has steamed, transfer it to a bowl and pour in the warm coconut sauce (save 0.5 cup for drizzling later). Gently fold the rice and let it sit for 30 minutes to absorb the flavors.

Peel and slice the ripe mangoes into thin strips or wedges.

To serve, place the sticky rice on a plate, top with mango slices, and drizzle with the reserved coconut sauce. Sprinkle with sesame seeds or mung beans if desired.