01 - Peel and thinly slice the onions into rings or half-moons.
02 - Combine flour, cornstarch, salt, black pepper, and paprika if using, in a large bowl.
03 - Separate onion slices and toss them in the dry mixture until evenly coated.
04 - Heat 2 to 3 inches of vegetable oil in a deep pan to 350°F.
05 - Shake off excess coating and fry onions in batches for 2 to 3 minutes until golden brown and crisp.
06 - Remove onions with a slotted spoon and drain on paper towels.
07 - Allow to cool slightly before serving or storing.