Place the sweet rice in a bowl and cover with water. Rub the rice between your hands. The water will become quite cloudy. Drain and repeat 3 more times. Fill the bowl again with water and let soak overnight at room temperature.

The next day, drain the rice and wrap in a cheesecloth. Place water in a pot with a steamer basket and bring to a boil. Place the steamer basket on top and place the cheesecloth on one side, leaving space for steam to rise up. Cover the pot and steam for 25 to 30 minutes.

While the rice is steaming, combine coconut milk, vanilla bean, cinnamon stick, one teaspoon salt, and coconut sugar. Heat until sugar has dissolved. Keep warm.

Once the rice is done steaming, transfer to a bowl. Remove the cinnamon stick from the coconut milk mixture. Remove the vanilla bean pod and scrape the seeds out from the pod. Return the seeds to the coconut mixture and discard the pod. Mix together until the seeds have mixed well. Pour half of the coconut milk mixture into the rice. Mix together, cover, and let sit for 25 minutes.

Combine the cornstarch and water in a small bowl. Reheat the sweet coconut milk and whisk in the cornstarch slurry until it thickens. Add the remaining salt and whisk in well. Before serving, mix the rice again and take a portion. Top with coconut syrup, sesame seeds, and mango slices.