Preheat the air fryer to 400°F (200°C).
Peel your onions and slice them into approximately 1/2 inch thick rings.
In a shallow dish, mix the all-purpose flour and salt. In another dish, beat the two eggs. In a third dish, place the Panko breadcrumbs. If you're adding any additional seasonings, mix them into the breadcrumbs now.
Dip each onion ring into the flour, shaking off the excess. Then, dip it into the beaten egg, making sure it's fully coated. Finally, dip it into the Panko breadcrumbs, pressing lightly to ensure the breadcrumbs stick.
Place the breaded onion rings in a single layer in the air fryer basket. Depending on the size of your air fryer, you may need to cook in batches.
Spray the onion rings lightly with the non-stick cooking spray. This will help them achieve a beautiful golden color.
Cook the onion rings at 400°F (200°C) for about 10-12 minutes, or until they're golden brown and crispy. Halfway through the cooking time, flip the onion rings or shake the basket for even cooking.
Remove the onion rings from the air fryer and serve immediately while they're still warm and crispy. Enjoy them with your favorite dipping sauce!