Rinse mangoes and chill them whole. Peel and slice mangoes just before serving to keep the fresh sweet taste. In a saucepan combine sticky rice and coconut milk and cook on medium heat for 5 minutes or until thick. Stir in vegan sugar and salt. The amount of sugar depends on the sweetness of the mangoes. Reduce heat to low and simmer, covered, for two minutes. Serve warm on a platter with chilled mango slices arranged around the edge.