Fill an Old-Fashioned glass with ice. Take a second Old-Fashioned glass and place the sugar cube, add the bitters, crush the sugar cube. Add rye whiskey or bourbon to the second glass with the bitters and sugar mix. Empty the ice from the first glass, coat the glass with the Herbsaint, discard any remaining. Empty the mixture from the second glass into the first glass and garnish with the lemon peel.