01 - If using fresh pineapple, peel, core, and slice into ½-inch thick rings. Pat thoroughly dry with paper towels to ensure batter adheres properly.
02 - Whisk together flour, cornstarch, sugar, baking powder, and salt in a medium bowl. Stir in cold sparkling water and egg if using until just combined—do not overmix to maintain light texture.
03 - Pour vegetable oil into a deep skillet or saucepan to reach 2 inches depth. Heat to 350°F, maintaining temperature throughout frying.
04 - Dip each pineapple ring into batter, allowing excess to drip off. Ensure even coating while preventing clumps.
05 - Carefully lower battered rings into hot oil in batches, avoiding overcrowding. Fry 1–2 minutes per side until deep golden brown. Remove with slotted spoon and drain on paper towels.
06 - Dust generously with powdered sugar and sprinkle with cinnamon if desired. Serve warm with vanilla ice cream or caramel sauce for optimal experience.