Final answer:
An Aperol Spritz is traditionally garnished with a slice of orange, which complements its bittersweet flavor and adds visual appeal.
Step-by-step explanation:
The traditional garnish for an Aperol Spritz is a slice of orange. This bright, citrus garnish complements the bittersweet flavor of the Aperol and adds a vibrant pop of color to the cocktail, making it even more appealing. To make a classic Aperol Spritz, you would combine Prosecco, Aperol, and a splash of soda water, then adorn the glass with a fresh orange slice to round out the presentation and add an extra layer of flavor.