In a shallow bowl, combine the flour, sugar, salt and cayenne. In another shallow bowl, beat egg and milk. Place cornflake crumbs in a third bowl. Pat green tomato slices dry. Coat with flour mixture, dip into egg mixture, then coat with crumbs.
In a large nonstick skillet, heat 4 teaspoons oil over medium heat. Fry tomato slices, four at a time, for 3-4 minutes on each side or until golden brown, adding more oil as needed. Drain on paper towels.
Place fried tomatoes on an ungreased baking sheet. Bake at 375 degrees for 4-5 minutes or until tender.