Heat coconut milk, sugar and salt over a low heat while stirring until the sugar and salt have dissolved.
Drain the rice, distribute it evenly in a steamer and steam over boiling water for 25 minutes. If you don`t have a steamer insert, you can put the rice in a saucepan and add enough water so that it is about 1 cm above the rice. Cook for 25 minutes as well. Then pour it into the coconut sauce and cover it for about 15 minutes.
Toast the sesame seeds in a pan without fat. Peel the mango and cut the pulp from the stone. Dice one half, puree the other with lime juice.
Shape rice into 12 balls with wet hands, pressing 1 piece of mango in the middle. Roll each ball in toasted sesame seeds. Serve with mango puree.