How to Make It
In a medium saucepan, combine the white wine with the crème de cassis, pomegranate juice, strawberry preserves and orange zest and bring to a boil, stirring to dissolve the preserves.
Add the plums, cherries and basil to the saucepan and return to a boil, then simmer over moderately high heat for 1 minute. Using a slotted spoon, transfer the fruit to a large glass or ceramic bowl. Add the grapes to the saucepan and simmer for 30 seconds; transfer the grapes to the bowl. Add the strawberries and blueberries to the saucepan and simmer for 2 minutes. Transfer the berries and cooking juices to the bowl and let cool completely; discard the basil sprigs. Cover and refrigerate the fruit soup until chilled, about 45 minutes.
In a small bowl, whisk the sour cream with the sugar. Spoon the fruit soup into shallow bowls and dollop the sweetened sour cream on top. Garnish the fruit soup with mint leaves and serve with toasted brioche, if you like.