In 1845, herbalist Bernardino Branca was trying to treat cholera in Milan, Italy. He concocted what may be the first fernet — an Italian type of amaro, or bitter herbal liqueur — using 27 herbs, roots, and spices. Little did he know, his recipe would remain intact for nearly two centuries and lead to the popular amaro Fernet-Branca.

"Fernet-Branca was born more as a medicine and not as a spirit," sixth-generation heir Edoardo Branca tells CNBC. Today, the bitter is universally popular in Argentina and gaining popularity in the US, particularly in San Francisco, where it was sold legally during Prohibition because of its medicinal properties.