Make a Manhattan without bitters by simply omitting that ingredient; bitters are always a purely optional component of the drink. Retain the other principal ingredients: whiskey, sweet vermouth and the classic maraschino cherry garnish.
To build the cocktail, first select the preferred whiskey base. About.com suggests that rye might make the best Manhattan; however, a great many other options, such as Canadian blended whiskey or Kentucky bourbon, are available. After the whiskey is selected, pour a half ounce of sweet vermouth over ice in a shaker, then add two ounces of the whiskey.
After these elements are combined in the shaker, the cocktail is then mixed together. Some purists insist that Manhattans should never be shaken but stirred; however, this is up to the palate of the person the drink is for. Once the elements are integrated, prepare the cocktail either straight or on the rocks. For straight, strain the Manhattan into a chilled martini glass. For rocks, prepare a small rocks glass or snifter by filling it with ice, then strain the cocktail over top.
As mentioned, the customary garnish for a true Manhattan is a maraschino cherry, a component that further helps to accent the sweet hues of the vermouth. Alternatively, some prefer to garnish their Manhattans with a citric component, such as an orange or lemon twist, to add a brighter, dryer, acidic note to the flavor profile.