A South Side or Southside is an alcoholic beverage made with gin, lime juice, simple syrup and mint. A variant, the Southside Fizz, adds soda water. Its origins are subject to speculation but the recipe can be traced back to at least 1916, when it appeared in Huge Enslinn’s book "Recipes for Mixed Drinks" as the South Side Fizz. The drink may have been the preferred beverage of Al Capone.
Add the mint leaves and lemon juice into a shaker and gently muddle.
Add the gin and simple syrup with ice, and shake until well-chilled.
Double-strain into a chilled cocktail glass.
Garnish with a mint sprig.