1 1/4 cups Cointreau or Grand Marnier
1 1/4 cups cranberry juice cocktail
1/2 cup plus 2 tablespoons fresh lime juice
3 tablespoons superfine granulated sugar
4 cups chilled Champagne or other sparkling wine
Stir together Cointreau, juices, and sugar and chill, covered, 2 to 6 hours. Just before serving, divide among 10 Champagne flutes and top off with Champagne.