There’s nothing to be bitter about — this category of tincture is an instrumental part of crafting many cocktails.

Bitters are made by infusing a neutral spirit with aromatic ingredients such as spices, fruit, tree bark, seeds and more. There have been a lot of new brands of bitters on the market recently, and chefs and mixologists now often create unique bitters of their own with flavors like Mexican mole, wildflower, black walnut etc.

Only a small amount of bitters is needed when making a cocktail: Two or three dashes usually does the trick, but those dashes are an essential component to classic drinks such as the Old Fashioned, the Sazerac and the Vieux Carré, lending them complexity and depth of flavor.

Market research firm Datassential says that bitters are now found on 21% of menus in the United States, a 42% increase over the past four years, and that 22% of the population has tried them.

Click through the gallery to learn more about this week’s Flavor of the Week and see how one restaurant is featuring bitters on its menu.