Add all the ingredients to a mixing glass filled with cubed ice, and stir until chilled.
Strain into a rocks glass filled with large-format ice and garnish with orange zest.
*Demerara syrup: Add 1/2 cup demerara sugar and 1/2 cup water to a small saucepan over medium heat. Stir until the sugar is dissolved. Strain into a jar and seal tightly with a lid. It will keep, refrigerated, for about 1 month.