Rinse and soak the glutinous rice for at least 1 hour in water. Afterwards, drain and steam in a bamboo basket or using a heat proof strainer. Cover it and cook on medium heat. After 15-20 minutes, you'll see the rice turn from white to a translucent color and soften. That's when the rice is ready.
For the sauce, heat the coconut milk on low heat. Add sugar and salt and stir occasionally. Once it's hot, turn off the heat and pour the coconut milk over the steamed rice, reserving half a cup to make the coconut sauce. Combine the water and cornstarch and mix throughly. Pour this slurry into the remaining coconut mixture and simmer until it's thickened, while stirring it together.
Cut up the mangoes into slices or cubes and serve with the coconut rice. Add coconut sauce and sesame seeds. Toasted coconut flakes are optional.
