For one cocktail, gather these items:
- 2 oz vodka
- 1 oz fresh grapefruit juice
- 0.5 oz simple syrup
- 0.5 oz fresh lemon juice
- Club soda
- 1 sprig fresh rosemary
- Ice cubes
- Grapefruit wedge for garnish
Use high-quality vodka for the best flavor. Fresh citrus juices make a big difference in taste compared to bottled versions.