Add the sugar and 400ml (13½fl oz/1½ cups + 1 tbsp) water to a medium saucepan. Place over a low-medium heat for 5 minutes, or until the sugar has dissolved. Increase the heat to medium and simmer for 5 minutes. Remove from the heat and allow to cool.
Add the mango, lemon juice and cooled sugar syrup to a blender. Blitz to a smooth purée. Pour into a Creami tub