Step 1.
- Chill the highball glass.
Step 2.
- In a shaker, combine gin, fresh lemon juice, simple syrup, and egg white.
Step 3.
- Dry shake (without ice) vigorously for about 15 seconds to emulsify the egg white.
Step 4.
- Add ice to the shaker and shake again until well chilled.
Step 5.
- Strain the mixture into the chilled highball glass.
Step 6.
- Top with soda water to fill.
Step 7.
- Garnish with a lemon slice.