Olive oil cooking spray
2–3 large onions
1/4 cup self-rising flour
2 eggs
2 cups fine dried breadcrumbs
1 teaspoon Cajun seasoning
Preheat the oven to 440°F. Line two large baking trays with baking parchment paper. Grease the paper with some olive oil spray.
Peel and slice the onions about 1/3- to 1/2-inch wide. Separate the rings, removing the very small rings from the center of the onion. You can freeze these for another time or use in another dish. Put the larger rings in a bowl of cold water.
Pour the flour into a shallow dish. Break the eggs into another dish, and lightly beat. Mix the breadcrumbs and Cajun seasoning in a bowl. Remove the onion rings, one at a time, and drain on paper towel. Coat each ring in flour, dip the ring in the egg, and then coat in the breadcrumb mix, shaking off any excess crumbs. Place the crumbed rings on the lined baking trays.
When all the onion rings are coated and on the trays, spray the onion rings with the oil, and bake for about 16 to 20 minutes. Turn after 8 to 10 minutes to brown both sides. Cook until golden brown and crispy. Once cooked, remove the onion rings from the oven, place them in a large bowl, and salt to taste.