At Cleveland’s rustic Greenhouse Tavern, the Franco-American cuisine has a compelling condiment companion: beer vinegar. You can detect it in dishes like the Pork Not Belly beer-vinegar-braised fried chicken and chanterelle mushrooms, but chef Brian Reilly recommends getting the full flavor in the simplest application: “The best, honestly, is on the fries. We make a vinegar with Maredsous, so it’s really tangy and goes well with our duck-fat fries.”

Make your own beer vinegar in five easy steps:

• Swirl 3 ounces of mother of vinegar in a growler. “It looks pretty gross, but it’s translucent,” warns Reilly. “It will take on the color of whatever beer you’re putting into it.”

• Pour a spoonful of dark brown sugar into the growler and fill it about 3/4 of the way with your beer of choice. Reilly says almost any style will work, from ciders to oatmeal stouts. “The best one I’ve made is with Stone’s Arrogant Bastard,” he says. “It still had the grapefruit and hoppy bitterness, but was also sweet.”

• Seal the growler with a coffee filter and a rubber band. “The bacteria are a living thing, so they have to breathe,” explains Reilly.

• Place the growler in a dark, cellar-temperature (50 to 62 degrees) space for approximately three weeks, until it’s turned. Taste-test to gauge the vinegar’s readiness; it will transform from stale beer to having unmistakable vinegar tang.

• Filter the liquid through a fine strainer into a bowl to remove the bacteria. Take the remaining vinegar and funnel it into a sterile bottle.