Chilled Mixed Berry Soup

Rinse berries, pat dry and cook with black currant juice and 2 tabalespoons sugar. Zest lemon, add zest to the juice and simmer for 5 minutes. Strain and collect the berry soup through a sieve. Stir the cornstarch into 1/2 cup cold water. Heat berry soup again, stir in the starch and cook over low heat for another 5 minutes. Squeeze lemon and combine the juice with 2 teaspoons sugar, then add to soup. Let cool and refrigerate.