01 - If using fresh pineapple, peel, core, and slice into 1/2-inch thick rings. Pat rings thoroughly dry with paper towels to remove excess moisture.
02 - In a medium bowl, whisk together flour, cornstarch, sugar, baking powder, and salt until well combined. Stir in cold sparkling water and egg (if using) until just combined—do not overmix as this affects texture.
03 - Pour vegetable oil into a deep skillet or saucepan to a depth of 2 inches. Heat oil to 350°F, maintaining temperature throughout frying for optimal results.
04 - Dip each pineapple ring into batter, ensuring complete coverage. Allow excess batter to drip off briefly to prevent uneven coating.
05 - Carefully place battered rings in hot oil, working in batches to avoid overcrowding. Fry for 1 to 2 minutes per side until golden brown and crispy. Remove with a slotted spoon and drain on paper towels.
06 - Dust warm fried pineapple rings generously with powdered sugar. Add a sprinkle of cinnamon if desired. Serve immediately while crisp, optionally with vanilla ice cream or warm caramel sauce.