(Be sure to read the Notes on the Old Bay seasoning before mixing.) In a medium bowl, add the Remoulade ingredients and stir to combine well. Set aside at room temperature if continuing with the recipe, or refrigerate if using more than 2 hours after making the sauce.
Place several layers of paper towels on a baking sheet or place a cooling/baking rack over a baking sheet. Set it aside. This will hold the finished tomatoes.
In a shallow bowl, whisk together the flour and cornstarch. Set aside.
In another shallow bowl, whisk the eggs, buttermilk, and hot sauce if using. Set aside.
In another shallow bowl, whisk the cornmeal, bread crumbs, salt, pepper, mustard, garlic powder, and onion powder. Set aside.
Place an empty baking sheet near the bowls. It will hold the breaded tomato slices before they are fried.
Pour about ½” of oil in a cast iron skillet or enamel covered cast iron skillet. (Cast iron will hold and maintain the heat better than a regular flying pan.) Heat the oil to 350 degrees F. Check your temperature with a thermometer.
While the oil is heating to 350° F, dip the tomatoes one or two at a time (or however many will fit into your bowl) into the flour, coating both sides. Shake off excess.
After the flour coating, dip the tomatoes into the egg mixture, coating both sides well.
Then dip the tomatoes into the breadcrumb mixture, pressing the breadcrumbs onto the tomatoes to give a good even coating. Place them onto the clean (no paper towels) baking sheet. Continue to coat all the tomatoes.
Once the oil is up to temperature, carefully add several tomatoes into the oil. Don’t overcrowd the pan. Fry for about 2 to 4 minutes per side, or until they are a nice golden brown on both sides.
Remove the tomatoes to the paper towels or rack for excess oil to be removed.
Continue this cooking process until all the tomatoes have been cooked.
Serve with the Remoulade.