This cops-and-robbers variant on the Dry Martini dates not to the Damon Runyon days of the 1930s but to the O. Henry days of a generation before. The name alludes less to its dash of absinthe, potentially torturous as that may be, than to its unusual dryness (these were mixed seven to one at a time when a standard Dry Martini was one to one). Of course, modern Martinis are far dryer—as are modern cops.
3 ounces Plymouth gin
Scant 1/2 ounce white vermouth
2 dashes absinthe or substitute (See Sazerac)
To finish: a cocktail onion
Stir and strain into a chilled cocktail glass; drop in the onion.