Peel the onions and slice off the ends. Using a mandoline or a sharp knife, slice the onions as thinly and uniformly as possible (about 1/8-inch thick). Separate the slices into rings and place them in a large bowl.

Drizzle the oil over the onion rings. Using your hands, toss thoroughly to ensure every strand is lightly and evenly coated.

Sprinkle the paprika, garlic powder, salt, and pepper over the onions. Toss again until the spices are evenly distributed.

Preheat your air fryer to 370°F (190°C) for 2-3 minutes if your model recommends it.

Working in batches to avoid overcrowding, place the seasoned onion rings in a single, even layer in the air fryer basket.

Air fry for 8-12 minutes, shaking the basket or tossing the onions with tongs at the 5-minute mark. Check every 2 minutes thereafter, as they can burn quickly. Cook until the onions are a deep golden brown, dry, and crispy.

Immediately transfer the crispy onions to a plate or tray lined with a paper towel. They will crisp up further as they cool. Let them cool completely before storing.