01 - Whisk together flour, cornstarch, sugar, cinnamon, and salt in a medium bowl. Gradually add cold sparkling water, whisking constantly until a smooth, thick batter forms.
02 - Pat pineapple rings dry with paper towels to ensure batter adheres properly during frying.
03 - Pour about 1/2 inch of vegetable oil into a large skillet. Heat over medium-high heat until oil shimmers and reaches frying temperature.
04 - Dip each pineapple ring into the batter, allowing excess to drip off for even coating.
05 - Fry pineapple rings in batches for 1–2 minutes per side until golden brown and crispy. Do not overcrowd the pan to maintain oil temperature.
06 - Transfer fried pineapple to paper towels to drain excess oil. Serve warm with honey or maple syrup, toasted coconut, or vanilla ice cream if desired.