Preheat oven to 425 degrees F. Line two baking sheets with parchment paper or silicone mats.
Slice the onions. Then, fill a bowl with cool water and place the onion slices in it while you prepare the breading stations.
Prepare 3 stations using shallow bowls or plates with rims. In the first bowl, mix together the flour, ½ teaspoon of the salt, and ½ teaspoon of pepper. After mixing well, remove about half of the flour mixture from the bowl to reserve for later. In the second bowl, beat the eggs with 2 tablespoons of water. In the third bowl, combine the panko, garlic powder, garlic salt, smoked paprika, parsley, and the rest of the salt (½ teaspoon). Mix well and remove half of this mixture from the bowl to reserve for later.
Remove an onion slice from the water and place it into the bowl with the flour mixture. Coat it with the mixture on both sides. Next, take the onion slice and dunk it into the egg mixture, also coating it on both sides. Finally, place the onion slice into the panko and coat it on both sides. Place the battered ring onto a prepared baking sheet. If you need more room on the baking sheets, you can put small onion rings inside larger ones.
Repeat step #4 until all of the onion rings are coated and placed on the baking sheets. When you start to run low on the flour and panko mixtures, refill their bowls with the second batches you reserved in step #3. This helps prevent the breading from getting too soggy and not sticking to the onion rings.
Spray rings with cooking spray before putting them in the oven (optional). Bake for 20 to 25 minutes, flipping each ring with tongs and rotating the baking sheets halfway through, until crispy and lightly browned.
Enjoy the onion rings immediately with your favorite dipping sauce!
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