Arrange the flour, egg, and panko breadcrumbs in three separate bowls. Combine the flour with paprika, garlic powder, salt, and pepper.
Slice the onions into rings around 1cm thick and dredge them in the seasoned flour. Remove and shake off the excess flour.
Place the floured onion rings into the egg mix, remove and shake off the excess.
Place the eggy onion ring into the breadcrumbs and cover evenly. Remove and shake off the excess.
Lay the onion ring in a flat layer, then repeat until all the rings are coated in breadcrumbs.
Preheat the air fryer to 180c and fry in a thin layer for 12-16 minutes until the onion rings are crisp and golden. You may need to do this in batches.
Season to taste and dust with a pinch of cayenne pepper.