Combine the sugar, grapefruit (give the grapefruit a squeeze so some of the juice goes into the pot!), vinegar, and rosemary in a small saucepan and simmer on low heat until dissolved about 15 minutes.

Let cool. Save in a sealable mason jar for up to one week.

In a cocktail shaker, mix 1.5 oz of gin or vodka with equal parts shrub mix. Or use sparkling water for a mocktail!

Shake and serve over ice with a grapefruit twist or sprig of rosemary.