The next day, rinse and drain the rice, repeating until the water runs clear.
Place it in a pan, cover with cold water and pop on the lid. Bring to a rolling boil, then simmer over a low heat for 5 minutes, or until all the water is absorbed.
In another pan, stir the coconut milk, sugar and ¼ teaspoon of salt over a medium heat. Bring it to the boil, then take off the heat.
Pour half over the rice and leave to absorb for about 2 minutes, or until the rice is soft. Pour the rest into a bowl. Chill both in the fridge.
Fold the coconut milk through the rice, then peel, destone and cut the mango into wedges. Serve with the sticky rice.