Frozen orange slices serve double duty as ice cubes and garnish in this bubbly elixir.
Arrange orange slices on a baking sheet lined with wax paper; freeze 30 minutes.
Meanwhile, combine 1/2 cup water and sugar in a 2-cup glass measuring cup. Microwave at HIGH 1 minute or until very hot. Stir until sugar dissolves.
Combine sugar syrup, juice, and liqueur in a pitcher; chill until ready to serve.
Place 1 frozen orange slice in each Champagne glass. Pour 1/4 cup juice mixture into each glass. Top with Champagne, and serve immediately.
Fresh tangerines and bottled juice may be substituted. Look for both in the produce section.
Christmas Through the South