Make the Mixed Berry Syrup: Combine a mix of berries (such as strawberries, blueberries, and raspberries) with sugar and water in a saucepan. Bring to a boil, then reduce to a simmer until the berries are soft and the mixture thickens. Strain the syrup and let it cool.

Prepare the Spritz: Fill a glass with ice, add the mixed berry syrup, and top with Prosecco and club soda. Stir gently to combine.

Garnish: Add a few fresh berries and a sprig of mint for a refreshing finish.