Purists frown on adding a maraschino cherry to an Old Fashioned cocktail, though this is how it’s typically served these days. The traditional recipe calls for a little pure cane syrup, a dash of Angostura bitters, a bit of orange peel, Bourbon and four ice cubes.
In New Orleans recently I discovered an interesting variation. At the restaurant Herbsaint I ordered an Old Fashioned and it was served with small peeled slices of orange and a couple of dried cherries which had been marinated in cherry liqueur. The marinated cherries were delicious, way more interesting than a bland, over-sweet maraschino cherry.
They added a distinct flavor to the drink — actually made it too fruity with the addition of the sections of orange — but on their own with just the traditional orange peel they would make a good substitute for a maraschino cherry, if a cherry is something you want in your Old Fashioned.