Rinse the Rice: Place the sticky rice in a bowl and cover with water. Let it soak for at least 4 hours, or overnight for best results. After soaking, drain the rice.
Steam the Rice: Fill a steamer or a large pot with water, and bring it to a boil. Line a steaming basket with cheesecloth or a clean kitchen towel. Add the soaked rice and steam for about 30-40 minutes, or until tender and translucent.
Prepare Coconut Sauce: In a saucepan, combine the coconut milk, sugar, and salt over medium heat. Stir until the sugar dissolves completely but do not let it boil. Reserve about ½ cup of the coconut sauce for drizzling later.
Mix the Rice and Sauce: Once the sticky rice is cooked, transfer it to a mixing bowl. Pour the remaining coconut milk mixture over the hot rice, and gently fold it in until fully combined. Allow the rice to sit for about 20 minutes to absorb the flavors.
Plate the Dish: To serve, scoop a portion of the sticky rice onto a plate, add sliced mangoes beside it, and drizzle with reserved coconut sauce.
Garnish: Sprinkle toasted sesame seeds over the rice and mango, and add a few fresh mint leaves on top for a burst of color and flavor.
Notes
Soaking the rice overnight yields the best results.