How to Make It
In a saucepan, bring the cassis, wine, brown sugar, cloves, star anise, cinnamon, zest and vanilla bean to a boil over high heat, stirring to dissolve the sugar. Reduce the heat and discard the flavorings. Stir in the rhubarb and return to a simmer. Remove from the heat and let stand for 10 minutes. Transfer to a bowl; refrigerate until chilled.
Spoon the soup into bowls. Top each with a scoop of ice cream and serve.