Soak gelatine in cold water. Heat the juice, wine and sugar and allow to cool slightly. Squeeze the gelatine and dissolve in the grape juice. Pour a little liquid into the bottom of 4 tartlet moulds (approx. 1/8 litre capacity) and leave to cool to set.
Wash the grapes and pluck them from the stems. Drain the cranberries on a sieve. Spread 1/3 of the fruit on each jelly in a star shape. Cover with liquid and let it gel again.
Repeat this process twice more, leaving some cranberries for garnishing. After the last layer of jelly, chill for another 1 1/2 hours. Dip the moulds briefly in hot water and turn the jelly out onto plates.
Garnish with remaining cranberries, mint and carambola slices. Vanilla sauce tastes good with it.