The bourbon cocktail made with mint, sugar, and water and associated with the Kentucky Derby is the mint julep.
A traditional mint julep combines bourbon, fresh mint—usually spearmint—sugar or simple syrup, water, and crushed or shaved ice. The mint is gently muddled or incorporated into the sweetened mixture, then bourbon and ice are added. It is commonly served in a metal julep cup, whose frosted exterior helps keep the drink cold.
The cocktail has deep roots in the American South. Early descriptions used different spirits, including rum, but bourbon became its defining base in Kentucky. One early printed description appeared in 1803, and Kentucky senator Henry Clay helped popularize the drink in Washington, D.C.
Churchill Downs has promoted the mint julep in connection with the Kentucky Derby since 1938. The drink is therefore strongly linked with Derby culture, though it is not the same as a mojito: mojitos typically use rum, lime, mint, sugar, and soda water. An Old Fashioned uses whiskey, sugar, bitters, and water, without mint as its defining ingredient.