Slice onion into large rings. In a shallow dish, whisk together egg and milk. In another shallow dish, whisk together flour, salt, pepper and paprika. In another shallow dish, place breadcrumbs.
Heat oil in either a large saucepan over medium heat or in a fryer to 375 F. coat onion rings first in egg mixture, then coat in flour mixture, return onion rings to egg mixture, then fully coat in breadcrumbs.
Fry onion rings in batches in the oil until browned. Place onion rings onto a wire rack over paper towels to drain.
