Dissolve the cornstarch in about one tablespoon of the juice.
Blend the remaining juice and the raspberries until smooth.
Sieve the blended juice and fruit into a saucepan. Add the cinnamon stick and bring it to a simmer. Once it simmers, add the mix of cornstarch and juice. Mix until the soup thickens a little. Add ground ginger to taste. Pour the soup into a plastic container to cool, with the cinnamon stick.
Once it's cool, plate it and garnish with fresh fruit.