This aperitivo from the walled city of Padua is based on an infusion of orange, rhubarb, china, and gentian. It's great for the Aperol Spritz (some use Campari, if they are unable to pin down a bottle of Aperol) 1oz Aperol with 2oz sparkling wine (try our Ca Furlan Prosecco) and a splash of soda. Serve well chilled in a flute glass and garnish with an orange slice.