Trim 1/2-inch from the stem and blossom ends of tomatoes. Slice tomatoes 1/4-inch thick.
Season tomato slices with 1 tsp salt and 1/2 tsp pepper; set aside.
In a shallow bowl, whisk together eggs and milk; set aside.
In a second shallow bowl, whisk together flour, 1/4 tsp salt, and 1/4 tsp pepper; set aside.
Place panko in a shallow bowl along with cornmeal, remaining 3/4 tsp salt, and 1/4 tsp pepper; stir to combine and set aside.
Working with one tomato slice at a time, coat tomatoes with flour mixture, shaking off excess. Coat with egg mixture, followed by breadcrumb mixture. Transfer to a wire rack set over a parchment-lined baking sheet; repeat the process with remaining slices.
Heat 1 cup of oil in a 10-inch skillet over medium-high heat until it reaches 350 degrees on a deep-fry thermometer.
Working in batches, carefully place tomatoes into the heated oil in a single layer. Fry until golden, turning once, 2 to 3 minutes per side. Drain on a paper towel-lined baking sheet.
After frying half of the tomato slices, discard oil and heat remaining 1 cup of oil in a skillet; continue frying remaining tomato slices.
Serve tomatoes immediately with aioli.
Note: Be careful when placing in hot oil, tomatoes are wet.