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. His version called for gin, lemon and lime juices, sugar, mint and club soda. Lose the bubbles and cull one of the citrus fruits, and you get the South Side as we know it today.

Multiple accounts peg the South Side’s creation to the 21 Club in New York, a bar that poured countless South Sides throughout the decades. But considering that the first iteration of the famous speakeasy didn’t open until 1922, it’s more likely that the bar popularized the drink rather than invented it.

Browse South Side recipes at cocktail bars today, and you will find some drinks made with lemon and others with lime. This citrusy kerfuffle may stem from Enslinn’s recipe containing both juices. It tastes great with lemon or lime, but the 21 Club served theirs with lemon, and so does this recipe.

When making the cocktail, treat the mint gently. Too vigorous a thrashing will highlight the herb’s bitter notes rather than its sweet and aromatic qualities. Double-straining the contents (straining the drink through a fine-mesh sieve) will ensure that none of the torn mint bits enter your glass and inevitably get stuck in your teeth.

Référence : https://www.liquor.com/recipes/south-side/