Place cucumber rounds in 6 oz of gin or vodka. Chill for at least 2-3 hours.
Before mixing, remove the cucumber from the alcohol- set aside for garnish. In a martini shaker, add ice, 1 oz of simple syrup, and 2 oz of the cucumber-infused alcohol. Shake for 30 seconds or until the shaker is frosted over.
Pour into a glass filled with ice, the shaker mixture, and top with tonic water. Garnish with strips of cucumber, the gin-infused cucumber rounds, and a pinch of mint. Serve chilled.