2/3 cup fresh lime juice
1/3 cup 100% pure pomegranate juice
1 cup Cointreau
1 cup 100% agave silver tequila (some of our favorites right now are Cazadores, Herradura and Tres Generaciones)
2 to 3 tablespoons superfine sugar
1 lime half for moistening the glass rims
Coarse (Kosher) salt
1 bottle chilled brut champagne or other sparkling white wine
In a pitcher, combine the lime juice, pomegranate juice, Cointreau, tequila, and the sugar. Mix until the sugar has dissolved. Cover and refrigerate until chilled, about 1 hour.
Moisten the rims of the champagne glasses with the cut side of the lime. Spread coarse salt on a small plate, then upend the glasses into the salt to crust the rims. Fill each glass halfway with the margarita base (it'll take a generous 1/3 cup). Slowly fill the rest of the way with champagne or sparkling wine, and hand to one of your lucky guests.