
Gentian liqueur is a bitter, yellow French aperitif liqueur built on gentian root. It is less sweet than most liqueurs, so in a drink it works more as a bitter than as a sweetener.
Another gentian liqueur
Suze, Salers and Avèze swap for each other in the same amount. Suze's main bottle is 15% with about 137 g of sugar per liter. Salers is 16%, and Avèze, at 15–18%, is sweeter.
Luxardo Bitter Bianco
The usual pick among other bitter liqueurs, at 30% and about 250 g of sugar per liter. Start with half the measure and taste. If the drink has syrup, it will need less.
Gentian eau-de-vie / Enzian
A distillate of fermented gentian root, at least 37.5% and unsweetened. Use about half the measure, plus about a barspoon of 2:1 syrup for every 30 ml replaced.
Gentian is usually one herb among many, and most amari are sweeter. A dark amaro also takes away the drink's pale color.
Greenhorn
Tequila blanco