Combine the cranberries, sugar, and water in a small saucepan over medium heat.
Bring the mixture to a gentle simmer, listening for the cranberries to start popping and releasing their color, about 10 minutes.
Use a fine sieve to strain the syrup into a bowl, pressing gently to extract all the vibrant red juice. Discard the solids.
Allow the syrup to cool completely, then refrigerate for at least 30 minutes to chill and thicken slightly.
Pour 1-2 tablespoons of the chilled cranberry syrup into each flute glass.
Gently top each glass with 3-4 ounces of chilled sparkling wine, pouring slowly to preserve the bubbles.
Gently stir the mixture with a spoon or stirrer to combine the flavors without losing too much fizz.
Garnish each glass with a few fresh cranberries and a sprig of mint for a festive touch.
Serve immediately to enjoy the lively bubbles and bright, tart flavor.