01 -
Rinse fresh rosemary sprigs thoroughly under cool running water and set aside.
02 -
Combine granulated sugar and water in a small saucepan. Stir continuously over medium heat until the sugar dissolves and the mixture is steaming or lightly simmering.
03 -
Add the rosemary sprigs to the saucepan, remove from heat, and allow the syrup to steep for 10–20 minutes, or up to 1 hour for a more pronounced herbal flavor.
04 -
Strain the simple syrup through a fine mesh sieve to remove the rosemary. Transfer the infused syrup to a glass jar or airtight container; refrigerate for up to 2 weeks.
05 -
Fill a glass with ice cubes to ensure a cold, refreshing beverage.
06 -
Pour fresh grapefruit juice, lime juice, and rosemary simple syrup (or agave) into the prepared glass. Stir well to blend flavors.
07 -
Adjust sweetness by tasting and adding additional rosemary syrup or agave as needed based on the tartness or bitterness of the grapefruit.
08 -
Pour club soda or sparkling water over the mixture just before serving to preserve carbonation.
09 -
Decorate with rosemary sprig, grapefruit slice, lime wedge, or rim the glass with sugar or salt as desired. Serve immediately.