Remove the kernels from each cob. The cleanest method is to place a small upside-down deli cup inside a large bowl, stand the corn cob on top of the cup, and cut downward along the cob. The kernels fall into the bowl without flying across the counter.
Add the flour, potato starch, tapioca starch, salt, and pepper directly to the bowl of kernels and toss to coat everything evenly.
Pour in the cold sparkling water and mix gently until a loose, shaggy batter forms around the corn. The batter should be just enough to bind the kernels together, not a thick coating. Do not overmix.
Fry immediately after mixing. The sparkling water loses its carbonation quickly and the gluten starts developing the longer the batter sits.
In a large pan, add about 1 inch of neutral oil and heat to 325°F (163°C) over medium heat. Keep the temperature consistent throughout frying.
Working in batches, scoop the corn mixture into the oil using a large spoon or ladle. Gently spread each scoop into your desired shape with the back of the spoon. They don't need to be perfect. The raggedy edges are the best part.
Fry for about 2 minutes per side until deeply golden and crispy all the way through.
Remove and drain on a wire rack. Season immediately with salt while still hot.
Serve immediately as is, or alongside kewpie mayonnaise and fresh shiso leaves.
