Slice onions into rings and separate the layers.
In a bowl, mix together flour, salt, black pepper, and paprika.
Dip each onion ring into milk, then dredge in the flour mixture.
Dip flour-coated onion rings back into the milk, then into the breadcrumbs, ensuring an even coat.
Heat vegetable oil in a deep fryer or heavy skillet to 375°F (190°C).
Fry the onion rings in batches until golden brown and crispy, about 3-4 minutes per batch.
Remove onion rings from oil and drain on paper towels. Season with additional salt if desired.
Serve hot as a snack or side dish.