Add all the ingredients into a mixing glass with ice, and stir until well-chilled.
Strain into a rocks glass over ice.
Garnish with a lemon and orange peel.
*Garam masala syrup: Bring 1 cup water to a simmer, remove it from the heat, and add 1 cup sugar and 2 tbsp, plus 2 tsp garam masala powder. Stir until the sugar dissolves, then let the spices steep for 10 minutes. Fine-strain out solids through a cheesecloth, and store in the refrigerator for up to 2 weeks.