Instructions
Chill cocktail glass. Stir whiskey, vermouth, and one dash of bitters over ice. Put the other dash of bitters in the cocktail glass. Strain into cocktail glass. Garnish with a maraschino cherry or a lemon twist.
Notes
I split the bitters between the shaker and the glass because I like to fortify the flavor of the bitters in this drink.
You may, of course, use bourbon instead of rye. I prefer rye. The ratio of whiskey to vermouth can vary from about 4:1 to 2:1.
Also, you can substitute Peychaud's or orange bitters.