In a large bowl, whisk together the flour, baking powder, salt, and cinnamon.
Gradually add the cold sparkling water, stirring until the batter is smooth and well combined.
Heat about 1 inch of vegetable oil in a deep skillet or frying pan over medium heat until it reaches 350°F.
Dip each pineapple ring into the batter, allowing any excess to drip off, then carefully place it in the hot oil.
Fry for about 2-3 minutes on each side or until golden brown.
Using a slotted spoon, remove the fried pineapple rings and place them on a paper towel-lined plate to drain excess oil.
In a small saucepan over low heat, combine the granulated sugar and vanilla extract, stirring until the sugar is dissolved.
Drizzle this syrup over the warm fried pineapple rings.
Serve immediately, optionally dusted with powdered sugar.