Begin by making the fry batter mix: combine the flour, cornmeal, 1/2 cup cornstarch, salt, pepper, cayenne pepper and granulated garlic in a lidded container. In a large and deep cast-iron skillet, heat 1 inch of oil to 350 degrees F over medium heat. Set up a dredging station with a plate containing the 1/2 cup cornstarch, a shallow bowl containing the buttermilk and a shallow bowl containing the batter mix. Working in batches, lightly press the tomato slices, one at a time, into the cornstarch, then dip them in the buttermilk, then lightly press them into the batter mix. Carefully slip the slices into the hot oil, three at a time, and cook for 1-2 minutes on each side, until golden brown. Remove from the oil with a spatula and drain on paper towels or a rack set over a paper towel-lined baking sheet. Let cool for 2-3 minutes before serving. Serve with the spicy remoulade sauce (recipe below).