Slice the tomatoes into 1/2-inch slices.
Place them on a wire rack over a sheet pan or on a flour sack towel or paper towel.
Liberally sprinkle both sides with kosher salt. And let sit for 15 minutes.
After 15 minutes, blot dry with a floursack towel or with paper towels.
While the tomatoes are resting, build your breading station.
You will need 3 shallow bowls for this.
In your first bowl, add the flour and a pinch of salt.
In your next bowl, add the egg, buttermilk, and a pinch of salt. And whisk well to combine.
In your third bowl, add the cornmeal and a pinch of salt.
After 15 minutes, blot your tomatoes dry with a floursack towel or with paper towels, and season both sides with kosher salt and freashly ground pepper. I like my pepper blend for this.
To bread your tomatoes, first dredge in the flour, then into the buttermilk and egg mixture, and then into the cornmeal. I set mine back on the rack after breading.
I like to let my tomatoes set for about 10 minutes to let the buttermilk and cornmeal soak in, and this helps the coating stay on while frying.
While you are waiting, add about 1/2 inch of oil to a cast iron skillet and bring the temperature up to 350°
Fry your tomatoes for about 2 minutes on each side or until nice and brown.
Again I set mine back on the rack to drain, and if you are making a lot, you can keep the rack in a warm oven while you work in batches.