Amaretto Sour

A sour built on amaretto, whose almond-and-stone-fruit sweetness is reined in by bright lemon and lifted by a silky egg-white cap. Introduced in 1974 as a recipe from the importer of Amaretto di Saronno, it became a 1970s and '80s mainstay — too often via sweet commercial sour mix — before bartenders restored fresh citrus and a dash of bitters to give it backbone. Shaken until foamy and served over ice with a cherry, it is approachable without being cloying.