01 - If using fresh pineapple, peel, core, and slice into 1/2-inch rings. Pat rings completely dry with paper towels to ensure batter adheres properly.
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 toughens the batter.
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 crispiness.
04 - Dip each pineapple ring into batter, turning to coat completely. Allow excess batter to drip off for a thin, even layer.
05 - Carefully place battered rings in hot oil, working in batches to avoid overcrowding. Fry 1–2 minutes per side until deep golden brown. Remove with 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 crispy, optionally with vanilla ice cream or caramel sauce.