Set up a dredging station with flour in one shallow bowl or container, buttermilk and egg whisk together in the second shallow container, and breadcrumbs and all the seasonings in the third container.
Cut the ends off of the onions and remove the outer papery layer and slice into desired thickness.
Separate onion slices and pair up with a smaller slice that will fit when a thin slice of cheese is added in between the two slices. *See above photo.
Slice mozzarella cheese into thin strips, about the same height as the onion slices, and place in between the two onion slices.
Heat oil to 350 degrees in a skillet, or large frying pan, over medium high heat.
Add onion rings into the flour mixture, then into the buttermilk mixture, and finally, into the breadcrumb mixture.
Carefully add a few onion rings at a time into the hot oil and fry on both sides until golden brown.
Remove from oil and place on a plate lined with paper towels.
Repeat the process until all the onion rings are fried and be sure not to overcrowd the pan.
Enjoy with your favorite dipping sauce.