1Puree mango with the sugar in a blender; set aside.
2Whip the whipping cream in a chilled bowl until soft peaks form. Set aside.
3Place the gelatin in a small heat proof bowl. Add the orange juice and cook in a water bath, stirring until the gelatin is dissolved. Or place in a microwave safe dish and cook for about a minute, checking often
4Place the mango puree and the gelatin in a large bowl. Carefully fold in the whipped cream.
5Transfer mixture to a plastic dish and place in freezer. Chill for at least 4 hours or until frozen
6To serve, scoop portions of mousse into ice cream dishes. Garnish with mint sprigs.