Step 1To make orange twists, slice the orange into quarters. Use a sharp knife to remove the flesh and pith from one quarter. Cut into even strips one-fourth-inch wide. Alternately, you can use the wide setting available on some zesters, or use a channel knife on the whole orange. Set aside.
Step 2In a cocktail shaker, combine the grapefruit juice and Campari. Fill with ice and shake until well chilled. Strain into a flute glass and top with Prosecco. Twist one orange strip over the drink and drop into the glass.