How to Make It
Preheat the oven to 400° and line a rimmed baking sheet with foil. Arrange the bacon on the foil and bake for about 15 minutes, until crispy. Drain the bacon and cut in half.
Meanwhile, put the flour, egg mixture and cornmeal in 3 shallow bowls. Season the cornmeal generously with salt and pepper. Dip the tomato slices in the flour, then in the egg and finally in the cornmeal, pressing to help it adhere. Transfer the slices to a wax paper–lined platter.
In a very large skillet, heat 1/4 inch of canola oil until shimmering. Add the tomatoes and cook over moderately high heat, turning once, until golden and crisp, 5 minutes. Drain the tomatoes on paper towels.
Lay 4 slices of toast on a work surface and lightly spread with mayonnaise. Top with the green tomatoes, bacon and arugula. Close the sandwiches, cut in half and serve.