Chill your champagne flutes in the freezer for at least 10 minutes to keep the drink cold and bubbly.
Combine the cranberries, sugar, and water in a small saucepan and bring to a gentle simmer over medium heat.
Simmer the mixture, mashing the cranberries with a spoon, until they burst and the syrup thickens slightly, about 10 minutes. You'll notice the berries releasing their tart juice and the syrup turning deep red and fragrant.
Pour the hot cranberry syrup through a fine sieve into a bowl, pressing gently to extract all the flavorful liquid. Let it cool to room temperature.
Once cooled, pour about 2 teaspoons of the cranberry syrup into each chilled flute glass. The syrup should be vibrant red and slightly sticky.
Gently pour the chilled sparkling wine or Champagne into each glass, tilting the glass slightly to preserve the bubbles.
Add a splash of fresh orange juice—about 1 teaspoon per glass—for a bright citrus note that balances the tartness of the cranberries.
Garnish each glass with a few whole cranberries and a twist of orange peel for a festive, colorful presentation.
Serve immediately, allowing the bubbles to settle slightly before sipping, and enjoy this sparkling, tart, and festive drink.