Cut the ends off of each tomato and then cut in half again so that you have 2 thick round slices of tomato. Mix flour and cornmeal together and set aside. Sprinkle each tomato half with salt pepper and thyme. Then press each tomato half into the cornmeal mixture, coating both sides.
Heat bacon fat in a cast iron skillet over medium heat and fry the tomatoes on each side until the crust is golden brown, about 3 minutes per side. Drain on paper towels and serve.