Chill a rocks glass with several ice cubes. Meanwhile, in another rocks glass, combine the rye whiskey, simple syrup, and bitters. Dump the ice from the first chilled glass and rinse the chilled glass with the Herbsaint. Stir the whiskey mixture 30 times. Strain the whiskey into the Herbsaint-rinsed glass. Rub a lemon peel around the rim and serve.