Rinse the glutinous rice under cold water until the water runs clear. This removes excess starch.
Place the rinsed rice in the rice cooker and add 1 cup of water. Cook according to the rice cooker instructions until the rice is tender and sticky.
While the rice is cooking, combine the coconut milk, sugar, and salt in a saucepan over medium heat. Stir until the sugar is dissolved. Do not let it boil.
Once the rice is done, transfer it to a mixing bowl and pour about 3/4 of the coconut sauce over the hot rice. Mix gently to combine and let it sit for about 10 minutes to absorb the flavors.
To serve, place a portion of the sticky rice on a plate, top with slices of mango, and drizzle with the remaining coconut sauce. Garnish with sesame seeds or mung beans if desired.
Notes
Use only glutinous rice, not regular white rice, for authentic sticky texture.