Sour is an essential cocktail component. That's why, every day, bartenders squeeze mounds of lemons and limes.
But look closely and you'll see another ingredient quietly adding its own tang to drinks: shrubs.
These complex and bright syrups — not to be confused with those green bushes that hide your neighbors' house — are made from fruit, sugar and vinegar. They have enough acetic acid to perk up your taste buds, but they also deliver unique layers of flavor.
"Shrubs are one of the best ways to get the fruit flavor into a drink without using juice," says Mark Church, a bartender at Grunauer in the Freight House District in Kansas City, Mo.
The word "shrub" derives from "shrab," an Arabic word for drink, according to Wayne Curtis' And a Bottle of Rum (Crown Publishers, 2006).
It makes sense, said cocktail historian David Wondrich. Citrus drinks were commonplace centuries ago, and lemon juice-based shrubs remained essential to proper punch into the 17th century when lemons were not widely available, says Wondrich, the author of Punch (Perigee, 2010).
"As early as the 1690s, people were substituting vinegar for lemon juice. If you do it right, it can be very tasty."
Shrubs were also a way to extend the harvest. Colonial Americans used fruit, sugar and vinegar to make a dense, intensely flavorful syrup that could preserve the pleasing bite of the fruit.
Colonists added rum and brandy to their shrubs, or sometimes simply diluted them with water. The non-alcoholic appeal of shrubs grew in step with the temperance movement of the 19th and 20th centuries, according to Homemade Soda (Storey Publishing, 2011), but then waned after Prohibition's repeal.
So what accounts for the shrub's revival?
Wondrich chalks it up to bartenders' enthusiasm for hand-crafting unique and sometimes forgotten syrups, bitters and other ingredients. "Bartenders are making shrubs their way using history as a starting place."
Shrubs aren't just for professional bartenders, though. They're easy to create at home, too, said bartender Church. "Shrubs are so simple to make," he says. "There's no wrong way to do it."
Shrubs make for an easy highball — just combine 1 ounce shrub with 1 ½ to 2 ounces spirits in a glass. Add ice and top with tonic or soda water. For a non-alcoholic savory refresher, combine 1 ounce shrub with about 8 ounces of fizzy water or unsweetened iced tea.