Steps

1. Chill a rocks glass.
2. In a mixing glass, muddle the sugar cube and bitters.
3. Add the rye, fill with ice, and stir until well-chilled.
4. Rinse a chilled rocks glass with absinthe.
5. Strain drink into the glass.
6. Twist a slice of lemon peel over the surface, then discard or use for garnish.