Zest then juice both Ruby Red Grapefruit (2).
Chop Fresh Cilantro (1 bunch).
Combine Natural Cane Sugar (1/2 cup) and Champagne Vinegar (1/2 cup) and shake til the sugar is dissolved.
Add the cilantro, grapefruit zest, and grapefruit juice to the sugar and vinegar mixture. Shake to combine then let sit in a cool, dark place for at least 24 hours and up to 7 days. Serve with prosecco or soda water!