To a mixing glass, add rye whiskey, simple syrup, and both bitters. Fill the glass three-quarters full with ice.
Using a bar spoon, stir until mixture is just combined and chilled, about 15-30 seconds.
Strain cocktail into chilled Old Fashioned glass, then fill glass half way with ice. Twist the orange peel and rub around the rim of the glass. Garnish with the orange peel.
Whiskey: Rye whiskey has a spicy, aggressive flavor and its mash must be made from at least 51% rye.
Simple syrup: To make it yourself, combine 1 cup water and 1 cup sugar in a small saucepan over medium heat. Stir until sugar is dissolved (do not boil). Remove from heat and cool before adding 1 tablespoon (or more to taste) to your cocktail shaker with the other ingredients. Store leftover simple syrup covered in the refrigerator for 3-4 weeks.
Sugar cube: To use a sugar cube, omit simple syrup in step 1. Add sugar cube to Old Fashioned glass after straining cocktail and combine using a muddler. Add ice and continue with step 2.
Yield: This recipe makes 1 cocktail.
Glassware: An Old Fashioned cocktail is traditionally made in an Old Fashioned glass, a 6-ounce to 10-ounce glass tumbler. Similar to a rocks glass or lowball glass, the Old Fashioned glass is decorated in the cut glass style.
Big batch: Old Fashioned cocktails are best blended individually, one drink at a time.
Brandy Old Fashioned: The most popular supper club drink in Wisconsin has brandy instead of whiskey, and its sweetened with maraschino cherry juice and grapefruit soda.
Fizzy Old Fashioned: A sweeter version made with blood orange soda.
Strawberry Old Fashioned: Muddle strawberries with the bitters in the mixing glass.