Step 1.
- Fill a highball glass with ice cubes.
Step 2.
- Add 2 oz of gin over the ice.
Step 3.
- Squeeze half a grapefruit into the glass, then drop in the spent half.
Step 4.
- Top off with tonic water to fill the glass.
Step 5.
- Stir gently to combine.
Step 6.
- Garnish with a slice of fresh grapefruit.