Citrus and ginger put a fresh spin on the traditional gin-and-lime-juice libation.
Simmer grapefruit juice, zest, sugar, ginger, and the water over medium heat 20 minutes. Let syrup cool; remove peel (use for garnish). Add lemon juice; refrigerate up to 2 weeks. To serve, combine 1 part gin with 2 parts syrup and pour over ice; garnish with peels.