Because limoncello is made from infusing alcohol with lemon zest (not juice), the Sorrento lemon's thick skin with its high lemon-oil content produces ideal limoncello.
In a glass measuring cup combine Limoncello, pineapple juice, apple juice, and Triple Sec. Fill an 8-ounce glass with ice. Pour mixture over ice. If desired, top with pineapple wedge and kumquat.