Make these alcoholic sparklers with orange-juice ice cubes.
Pour orange juice into 2 ice-cube trays; freeze until solid, at least 3 hours and up to 1 week.
Divide orange-juice cubes among 8 glasses. To each glass, add 1/4 cup dry vermouth, 1/2 cup club soda, and a dash of bitters. Garnish with orange slices, if desired.