To make this recipe fit for a gluten-free diet just replace the all-purpose flour with your favored gluten-free flour mix. Make sure to use panko bread crumbs that are approved as gluten-free. You can find brands of gluten-free panko, in the market. As always recollect to check all ingredient labels to make sure there are no additives that contain gluten and take safeguards to prevent cross-contamination during preparation. Relish your gluten-free onion rings!