This drink combines sweet-tart grapefruit juice and gin with sparkling wine for an effervescent cocktail that's perfect for toasting the holiday season.
In a punch bowl or large pitcher, combine gin and sugar. Stir until sugar dissolves, 1 minute. Add grapefruit juice and bottle of sparkling wine; stir to combine. To serve, fill 6 glasses with ice and wine mixture, then garnish with thin lemon slices.