For the soup: boil peaches in water, rinse, peel, pit and finely slice. Carmelize sugar until golden-yellow and slowly stir in the sweet wine. Cook the peaches in the syrup, covered, for 1-2 minutes. Season with peach liqueur and lemon juice and let cool.
Keep in the refrigerator until ready to serve.
To serve: infuse the peach soup with some champagne, pour into chilled bowls and serve garnished with currants and mint.