Rinse the Glutinous rice (Thai sticky rice) under cold water until the water runs clear, then soak it in plenty of water for at least 4 hours or overnight.
Drain the soaked rice, place it in a steamer lined with a clean cloth or banana leaf, tuck a Pandan leaf into the rice for fragrance, and steam until the grains are tender and translucent, about 20–30 minutes depending on your steamer.
While the rice is steaming, warm the Full-fat coconut milk with Granulated sugar and a pinch of Sea salt in a saucepan over low heat—stir just until the sugar dissolves and do not let it boil. Reserve about a third of this mixture to serve as a glossy topping.
To make a slightly thicker drizzle, mix a small amount of the remaining coconut milk with Rice flour to form a smooth slurry, then stir it back into the pan and simmer gently until it thickens slightly; remove from heat.
When the steamed rice is done, transfer it to a bowl, pour most of the remaining warm sweet coconut mixture over the hot rice, fold gently to coat, then cover and let it rest 10–15 minutes so the rice absorbs the sauce and becomes glossy and fragrant.
Toast the Split mung beans in a dry skillet over medium heat, stirring frequently, until golden and aromatic; cool and break up slightly for a crunchy topping.
Peel and slice the Mango into generous wedges or slices.
To serve: spoon a mound of the coconut‑soaked sticky rice onto a plate, arrange the mango slices alongside, drizzle with the reserved thicker coconut sauce, and finish with a sprinkle of toasted split mung beans and an optional pinch of sea salt to taste.
