The next time you walk into a restaurant and see a stately oak barrel, don’t be so quick to assume it’s full of booze. For centuries, wooden barrels have been used to age wine, whiskey and other liquors, and now local chefs and gourmands are applying the same technique to give their condiments and sauces a mellow, oaky flavor.

The concoctions take on components of the barrels — often bought or donated from local distilleries that once used them to age spirits — including vanillin (an organic chemical compound that gives vanilla its distinct flavor and smell), wood tannins and the essence of the liquors that once sloshed around inside.

“The technique itself is getting more widely used,” says Adam Howard, chef de cuisine at Range. “In the last couple of years, people have gotten back into a little more soulful, a little more rustic approach to [cooking].”
Last summer, Range purchased 200 pounds of hot chilies from Big White Barn Produce in Frederick, Md. Unsure at first how he’d use so much heat in the kitchen, Howard decided to ferment the produce haul with peaches and then age the mash in barrels that once held mescal to make a smoky hot sauce with a hint of sweetness and a fiery finish.

“It’s hot but it has a lot of interesting characteristics to it besides just ‘burning,’ ” says Howard, who uses the hot sauce in a beurre blanc sauce with fried pig ears and green tomato pickles ($9) and as a spicy cocktail sauce at the restaurant’s raw bar.

The barrel-aging treatment also works with more international cuisines. At Korean food favorite Mandu, co-owner Danny Lee drummed up an idea for a barrel-aged soy sauce with friends from the Chinatown eatery Sixth Engine, who had an old rye whiskey barrel donated to them from Catoctin Creek Distilling Company in Purcellville, Va. They filled the barrel to the brim with 35 gallons of soy sauce and let it sit for six months.
“We had no idea what to expect,” Lee says. “We basically tasted it every two weeks or so and made notes.”

The end product was a mellow, almost buttery soy sauce that tasted less salty due to the infusion of sugars from the rye-soaked barrel. Mandu and Sixth Engine give bottles away as gifts to friends and regulars at their restaurants, and Lee incorporates the sauce into specials at Mandu, including rabokki (a hybrid of ramen with fried rice cakes, $16) and tteokbokki (a spicy Korean snack food, $16). At Sixth Engine, executive chef Paul Madrid uses the barrel-aged soy sauce on the sweet and spicy wings ($12).

Next, Lee and Madrid plan to age vinegar in the now rye-and-soy-sauce-soaked barrel, and then even try their hand at some kind of booze aged in the same barrel.

If a whiskey-soy-vinegar martini doesn’t sound enticing, consider something a little sweeter. In a warehouse in Northeast D.C., Art Drauglis barrel-ages his Langdon Wood maple syrup in whiskey, bourbon or brandy barrels from Catoctin Creek and other distilleries. His syrup is available online and in local shops and is occasionally featured in restaurants such as Bistro Bohem, where it’s drizzled onto the chicken schnitzel and waffle ($14).

Though barrels can be reused, Drauglis learned — after about 10 batches — that they do have a shelf life.

“The last thing that was in there was just kind of nasty,” he says of the super-syrup-soaked cask that he first started experimenting in several years ago.