CUT cauliflower into 1/2-in.-thick slices. Beat egg in a pie plate. Stir panko with parmesan on a large plate. Pour canola oil into a large frying pan set over medium-high. Dip each cauliflower slice in egg, then coat with panko mixture. Pan-fry in oil until golden, 2 min per side. Transfer to paper-towel-lined plate.
WHISK mayo with prepared relish, onion powder, paprika, white vinegar and garlic powder in a small bowl. Drizzle over cauliflower.
How to shop for, prepare and cook with cauliflower