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 steam it in a bamboo or metal steamer lined with cheesecloth for about 20-25 minutes, or until the rice is tender and sticky.
Meanwhile, in a small saucepan, combine the coconut milk, sugar, and salt. Heat gently over medium heat until the sugar is dissolved; do not let it boil.
Once the rice is cooked, transfer it to a large bowl and pour about 1 cup of the warm coconut milk mixture over the rice. Stir well to combine, then let it sit for about 20 minutes to absorb the coconut milk.
To serve, take a portion of the sticky rice and mold it into a small mound on a plate.
Top with sliced mangoes and drizzle some of the remaining coconut milk over the top.
Sprinkle with sesame seeds and garnish with fresh mint leaves for a pop of color.