Beat the eggs in a bowl. Mix the flour, salt, pepper and oregano in a 4L resealable plastic bag. Dip each eggplant slice in the egg then drop the eggplant in the flour mixture one at a time, shaking the bag to coat the eggplant.
Heat the vegetable oil in a large, deep frypan over medium heat. Place the eggplant slices in the frypan to cook, turning occasionally until evenly browned. Drain the eggplant slices on a paper towel-lined plate. Arrange the eggplant in one layer on a baking tray. Spoon enough pizza sauce to cover each eggplant slice. Top each eggplant with mozzarella cheese.
Bake in the preheated oven until the mozzarella cheese is melted, 5 to 10 minutes.