Adapted from 3-Ingredient Cocktails by Robert Simonson Suze is a bitter apéritif that gets its flavor, and strength, from gentian roots. It's fairly prominent in this drink, which is great if you like cocktails on the bitter side, as I do. Similar gentian-based apéritifs include Avèze and Salers and could be used in place of the Suze. For those who like their drinks on the less bitter side, increase the gin to 1 1/2 ounces and reduce the Suze to 1/2 ounce.