Heat oven to 425 degrees F. Line a sheet tray with parchment paper or aluminum foil.
Cut onion into slices.
Add flour, salt, pepper, garlic powder, paprika, and dried oregano to a small bowl and stir.
Add egg to a second small bowl and beat.
Add Panko to a third small bowl.
Dip each onion slice first in the flour mixture, then the egg, and then the Panko.
Place the onion slices on prepared baking sheet
Repeat process with all the onion slices.
Bake at 425 degrees 20 minutes or until golden brown.