*Using two Old Fashioned glasses to mix the drink is a ritual that harkens back to the original first recipes in print.
Pack one Old Fashioned glass with ice. Set aside to chill. In another Old Fashioned glass, muddle sugar cube with bitters. Add several ice cubes and rye whiskey. Stir thoroughly to chill.
Discard the ice in the first chilled glass and add absinthe (or Herbsaint). Swirl to fully coat the glass, and shake out excess liquid. Strain the cold rye whiskey and bitters into the absinthe-coated glass. Garnish with a twist of lemon peel.