Step 1Fill the cocktail glass with ice and allow to chill. In a cocktail shaker, muddle together the sugar with one-half teaspoon water. Add a few ice cubes to the shaker, along with the whiskey, bitters and lemon twist, and stir the mixture until it is cold.
Step 2Discard the ice in the cocktail glass and add a dash of absinthe to the glass. Swirl the glass to allow the absinthe to coat the interior. Strain the cocktail into the glass and serve with a glass of ice water on the side.