Within cocktail culture, the classic recipes more often than not have a story about the origen of the drink. The classic Sidecar is no exception. Invented some time around World War 1, two bars (a French and an English) claim to have created the drink for a customer who arrived in the sidecar of a motorcycle. Another version refers to serving the drink in a coupe glass with the remains from the shaker served in a shot glass as the “sidecar” (kind of a sophisticated European version of the “Shot and a Beer”). The original recipe for the Sidecar called for equal parts cognac, Cointreau, and lemon juice (1:1:1). Today, depending on the recipe you’re looking at, the Sidecar calls for cognac or brandy, orange liqueur, and lemon juice. The proportions have also changed reducing the proportion of orange liqueur and lemon juice (2:1:1/2). I come down on the side of a slightly less acidic version with a more pronounced orange note (2:2:1/2). You should experiment and decide your proportions for your own Sidecar. Tchin! Tchin!

Sidecar Cocktail
1 drink and a “sidecar”

Ingredients:

1 ½ ounces cognac or brandy
1 ½ ounces orange liqueur (Cointreau, Gran Marinier, Triple Sec)
¾ ounce lemon juice.
granulated sugar for the rim of the glass

Combine the first three ingredients in a shaker with ice. Shake and strain into a cocktail glass (eg. coupe or small martini glass) rimmed with sugar. If you opt for a more acidic version of the Sidecar, the sugared rim helps to balance each sip. You decide for yourself.

https://www.liquor.com/recipes/sidecar/
The Art of the Cocktail: Philip Collins, Chroniclebooks LLC; 1944