Peel the onions and cut them into 1/2- to 3/4-inch thick slices. Separate the slices into rings. Keep a few of the larger outer rings intact.

In a shallow bowl combine flour, cornmeal (if using), baking powder, salt, pepper, smoked paprika, and cayenne. Whisk to evenly distribute.

In a separate bowl whisk the eggs and buttermilk together until smooth.

Put panko breadcrumbs in a third shallow bowl. Optionally add a pinch of salt and a little paprika for color.

Dredge the onion rings first in the dry flour mixture, shake off excess, then dip into the buttermilk-egg mixture, and finally press into panko breadcrumbs so they’re fully coated. For an extra-thick crust, repeat the egg and panko step once more.

Pour oil into your skillet or Dutch oven to a depth of about 2–3 inches. Heat to 350°F (175°C). Test with a small breadcrumb.

Fry the coated onion rings in batches for 2–3 minutes per side until deep golden brown and crisp. Use tongs to flip gently.

Transfer fried Tennessee Onions to a paper towel-lined tray or wire rack. Sprinkle lightly with flaky salt and a tiny dusting of sugar if desired.

Serve immediately with dipping sauces such as ranch, spicy mayo, or a tangy vinegar-based slaw.