Step 1.
- Fill a shaker with ice.
Step 2.
- Add 2 ounces of gin, 1 ounce of freshly squeezed grapefruit juice, 0.75 ounces of simple syrup, and 0.5 ounces of lemon juice to the shaker.
Step 3.
- Shake well until chilled.
Step 4.
- Strain the mixture into a chilled cocktail glass.
Step 5.
- Garnish with a slice of grapefruit.