Peel the mangoes, remove the stones and roughly chop the flesh. Purée the mangoes with the mango sorbet and half the apple juice. Set aside to chill.
Purée the blackcurrants with the rest of the apple juice.
Spoon the mango smoothie into 2 short glasses. Place a spoon on the surface of the mango, holding it as flat as you can, and pour on the blackcurrant purée. Drag a teaspoon or skewer down the inside of the glass, to make vertical stripes around the glass.