For the rosemary-vanilla syrup: In a small saucepan over medium heat, combine the sugar, water and rosemary sprigs. Cook for 5 minutes or until simmering, stirring to dissolve the sugar. Stir in the vanilla extract, remove the pot from the heat and let sit for 10 minutes.
Discard the rosemary sprigs, transfer the rosemary-vanilla syrup to an airtight container and let cool in the refrigerator for 1 hour. The syrup can be stored in the refrigerator for up to 2 weeks.
To make one mocktail: In a cocktail shaker filled halfway with ice, combine the pink grapefruit juice, lemon juice and rosemary-vanilla syrup. Shake until chilled through.
Strain the cocktail into a highball glass filled ⅓ of the way with ice. Top with sparkling water.
Garnish with a rosemary sprig and pink grapefruit slice. Enjoy!
Recipe adapted from: Kari Skelton