Cut cheesecake slices into smaller portions (about 4-6 portions per slice). If the cheesecake is too soft, place it in the freezer for a while to harden it up and then try cutting it.
Heat oil in a deep-fryer or in a small, deep pot to about 340 degrees Farenheit.
Making the tempura mix: in a container, combine the wheat flour, rice flour, corn starch, baking powder, and salt. Mix with a fork. Then add the egg and cold soda water. Mix with the fork to produce a lumpy batter.
If you are using a pot for the frying, test the oil temperature by dropping a tiny bit of tempura batter into the oil. It should descend slightly beneath the surface then rise up. If it goes too far down to the bottom, then rises, it is not hot enough.
Once the oil is at the proper temperature, dip cheesecake pieces into the batter. Then dip into the panko breadcrumbs if you are using them, then carefully place them in the oil. Fry for about 5-7 minutes. Make sure that between frying batches you store the batter in the freezer to keep it cold. The colder the batter, the crispier the cheesecake bites will be.
Arrange fried cheesecake bites in bowls with an optional scoop of ice cream per bowl. Enjoy!