Prepare the onions by slicing them into thick rings.
Soak the onion rings in ice water.
Prepare the mozzarella by cutting it into sticks or slices.
Set up your breading station with flour, beaten eggs, and breadcrumbs.
Coat each onion ring before stuffing it with mozzarella.
Stuff the coated onion rings with mozzarella sticks.
Heat oil to 350°F (175°C) in a deep frying pan.
Fry the stuffed onion rings in batches until golden brown.
Remove the onion rings and drain on paper towels.
Allow to cool slightly before serving with your favorite dips.