Soak the glutinous rice in water overnight.

Rinse the rice several times until the water runs mostly clear. Drain it well in a fine-mesh strainer.

Fill a pot with water and bring it to a boil. Line a steamer basket with a clean tea towel or cheesecloth and spread the drained rice evenly over the cloth. Cover and steam for 20 to 25 minutes, or until the rice is tender and translucent.

While the rice is steaming, combine 200 ml coconut milk, sugar, and salt in a saucepan. Cook over medium heat, stirring occasionally, until the sugar dissolves and the mixture comes to a gentle simmer. Remove from the heat. Time this step so the coconut milk mixture finishes cooking around the same time as the rice.

Transfer the hot cooked rice to the coconut milk mixture and stir until evenly coated. Cover and let rest for 10 minutes. Stir again, cover, and let rest for another 20 minutes.

To make the coconut sauce, combine 200 ml coconut milk and cornstarch in a small saucepan. Cook over medium heat, stirring constantly, until the sauce thickens slightly. Remove from the heat.

Divide the sticky rice among serving plates. Top with sliced mangoes and drizzle with the coconut sauce. Sprinkle with sesame seeds and serve. Enjoy!