"Magic or medicine?” That’s the question Tenzing Momo employees usually ask Anna Wallace when she walks into the Pike Place Market herbal apothecary. The answer, she says, is both. Wallace develops cocktails for local bar impresario Linda Derschang, and she’s here seeking ingredients destined for housemade bitters—an aromatic, alcoholic infusion of macerated plant roots, bark, herbs, spices, and fruit that has long been used to remedy digestive distress, among other ailments.

But a dash of bitters is also an essential component in some of our country’s greatest cocktails: the old-fashioned, the Manhattan—even the original martini called for orange bitters. Seattle mixologists already crafting their own fruit juices, syrups, and sodas have turned their attention to making bitters—researching recipes in vintage cocktail books like Jerry Thomas’s 1862 bible, The Bar-Tender’s Guide, and Web sites like Seattle-based Jamie Boudreau’s blog. Boudreau, who directs the bar at Tini Bigs Lounge in Lower Queen Anne, makes two versions of the spirit and uses them to “balance a slightly sweet drink and offer complexity.” He is quick to remind me that, according to its first written definition from 1806, “a cocktail can’t be called such unless bitters is an ingredient.”

Back in January, Anna Wallace invited me to an afternoon bitters mixing session. As I sat amid her stash of cigar boxes filled with fragrant bags of cardamom, snakeroot, gentian, cinchona bark, quassia, and milk thistle (which is said to restore the liver), I sampled three blends steeping in tall glass jars that would require weeks of regular agitation, filtering, and tasting before they would be called into service behind the bar.

Today one of those blends, a blood orange–laced version, is featured in the Oddfellow, signature cocktail at Derschang’s newest venture on Capitol Hill, Oddfellows Cafe and Bar. The drink is served on the rocks and garnished with an orange slice and an amarena cherry, and calls for bourbon, Cointreau, fresh lemon juice, and a dash of Wallace’s bitters. Your lips pucker just thinking about it, but the drink hits a perfect balance of sweet and sour, and the bourbon comes through just enough to let you know it means business.