1.Grease a 19cm x 29cm slice tin. Line the base and sides with baking paper.
2.Sprinkle the gelatine over the cold water in a small bowl.
3.Place the sugar and extra water in a medium, heavy-based saucepan. Stir over a low heat until sugar dissolves. Bring to the boil. Stir in the gelatine mixture; boil, uncovered, without stirring, for 20 minutes. Transfer to a medium bowl; cool to lukewarm. Add vanilla and juice.
4.Beat the mixture with an electric mixer, on high speed, for about 4 minutes or until very thick and white. Quickly spread into prepared pan. Stand at room temperature for about 2 hours or until set.
5.Meanwhile, place coconut in a heavy-based frying pan. Stir over a medium heat until coconut is golden brown. Tip coconut immediately onto a tray, as it will continue to cook if left in pan.
6.Cut marshmallow into squares; roll squares in the coconut. Serve.
Not suitable to freeze or microwave.Note