01 - Rinse the glutinous rice under cold running water until the water runs clear. Submerge the rice in fresh water and allow it to soak for a minimum of 4 hours, or preferably overnight.
02 - Drain the soaked rice thoroughly. Transfer the rice to a steamer lined with cheesecloth (bamboo or metal steamer is suitable) and steam for 25 to 30 minutes, or until the grains are tender and translucent.
03 - While the rice is steaming, gently heat 1 cup of full-fat coconut milk in a saucepan over medium heat. Stir in 1/3 cup granulated sugar and 1/4 teaspoon salt until fully dissolved. Avoid boiling the mixture. Once cooked, immediately transfer the hot steamed rice to a large mixing bowl. Pour the sweetened coconut milk over the rice, mix until well-combined, cover, and let it rest for 15 minutes to allow the rice to absorb the liquid.
04 - In a small saucepan, combine 1/4 cup coconut milk, 1 tablespoon sugar, 1/4 teaspoon salt, and 1 tablespoon rice flour or cornstarch. Cook over medium heat, stirring continuously, until the mixture thickens to a pourable consistency. Remove from heat and allow to cool.
05 - Spoon a portion of the infused sticky rice into individual dessert cups. Arrange the sliced mangoes artfully on top of the rice. Drizzle generously with the prepared coconut topping.
06 - Optionally, sprinkle with toasted sesame seeds or mung beans. Add fresh mint leaves for a final touch. Serve at room temperature or slightly chilled.