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

Drain the rice and place it in a steamer lined with cheesecloth. Steam the rice for about 30 minutes until tender.

In a saucepan, combine coconut milk, sugar, and salt. Heat over medium heat until the sugar dissolves, but do not boil.

Reserve 1/4 cup of the coconut sauce for drizzling later.

Once the rice is cooked, transfer it to a mixing bowl and pour the remaining coconut sauce over it. Stir to combine and let it sit for about 10 minutes.

To serve, place a portion of the sticky rice on a serving dish, top with sliced mango, and drizzle with reserved coconut sauce. Sprinkle with toasted sesame seeds if desired.