01 - Combine dark rum and brown sugar in a shallow dish. Add pineapple pieces, turning to coat evenly. Let soak for 10 to 15 minutes, flipping halfway through to ensure absorption.
02 - Whisk together flour, cornstarch, and salt in a medium bowl until well combined. Gradually whisk in cold sparkling water until a smooth, thick batter forms without lumps.
03 - Pour 1 inch of vegetable oil into a large skillet or deep pan. Heat over medium-high heat until temperature reaches 350°F.
04 - Remove pineapple from rum mixture and pat dry with paper towels. Dip each piece into batter, allowing excess to drip off for even coating.
05 - Fry pineapple pieces in batches for 2 to 3 minutes per side until golden brown and crispy. Avoid overcrowding the pan to maintain proper oil temperature.
06 - Transfer fried pineapple to paper towel-lined plate to drain excess oil. Serve warm, drizzled with honey or maple syrup and sprinkled with cinnamon. Accompany with vanilla ice cream or whipped cream if desired.