To make tempura batter, mix the flour, cornstarch, and baking powder in a large bowl and add seltzer in a stream while whisking constantly. Season with salt and pepper.
Heat canola oil to 375 degrees F in a deep fryer. Spread coconut on a utility platter. Place slices of cheese on a slotted spoon and ladle tempura batter over. Deep-fry in the basket of a deep-fryer until golden brown, briefly drain then transfer to the plate of coconut so that the coconut will stick to the surface while the batter is freshly fried and still hot.
Serve with small skewers or cocktail toothpicks.