Prepare the sticky rice by steaming glutinous rice inside a cloth bag using a vegetable steamer.
In a small saucepan, stir 1 cup of coconut milk together with 3 tablespoons of sugar and 1/2 teaspoon of salt. Heat only until the sugar and salt dissolves. Soak the cooked sticky rice in this mixture.
Blend the 1/2 cup coconut milk, salt, sugar and starch. Whisk and heat in a small pan until thickened, then cool in the refrigerator until ready to serve.
Use a small flat pan to toast the sesame seeds until golden brown.
Peel and cut the mango and arrange it with the sweetened rice. Sprinkle the rice with a little toasted sesame seed. Drizzle a little of the very cold sauce over it all. Serve.