Add mint, lime, gin, and sugar (if using) to shaker and muddle.
Add cucumber slices to shaker and shake vigorously.
Pour mixture over glass filled with ice and top with tonic water.
Stir, let set for a few minutes for the flavors to enhance and enjoy.
*For those who prefer a sweeter drink, add sugar to taste. However, it's also quite enjoyable without. *Questions about substitutions, equipment, or troubleshooting? Check out our Recipe FAQ page. *Nutrition information is a rough estimate.