Slice tomato into ½-inch thick slices. Sprinkle with salt on both sides and set slices on paper towels to drain for 10 to 15 minutes. Pat the slices lightly with a clean linen or paper towel before proceeding.
Set Up Breading Station: combine flour and zest and place on a large plate (or wax paper for easy clean up). Place the egg in a wide shallow bowl, season with salt and pepper, and lightly beat with a fork. Spread the panko breadcrumbs on a separate large plate or sheet of wax paper. Lightly dredge the tomato slices in flour, dip into the egg wash, and coat both sides generously with panko breadcrumbs.
Meanwhile, add a thin layer of oil (roughly ¼ to ½-inch deep) in a large sauté pan and place over medium-high heat.
Once the oil is hot, gently add the breaded tomato slices and fry for 1 to 2 minutes on each side or until golden brown. Avoid over-crowding the pan, frying the tomatoes in batches if needed. Transfer the fried tomato slices to a wire rack and immediately sprinkle with salt. Serve hot with lemon wedges.