Peel the mango and cut into cubes. Set aside 2 to 3 of the cubes to later cut into smaller pieces to garnish the top of the mousse. Place the rest of the mango in a food processor with the icing sugar. Pulse until smooth, and then pour into a medium-sized bowl. Place the orange and lime juice in a small bowl. Sprinkle in the gelatine and let stand 5 minutes. Mix in the boiling water. Whisk gelatine mixture into the mango puree. Refrigerate 45 minutes, or until the mixture begins to thicken slightly. Whip the whipping cream until stiff peaks form. Whisk 1/4 of it into the mango mixture to lighten it, and then gently fold in the rest of the whipped cream. Divide and spoon the mixture into 6 martini, wine or other decorative glasses. Chill at least 4 hours, or until set. (Can be made a day in advance). Garnish the top of the mousse, if desired, with a little whipped cream, some small cubes of mango and a mint sprig.
The mousse will take about 45 minutes to set.