Heat 1 cup of the olive oil in a large skillet. Cut eggplants into thin slices. Fry half of the slices until golden on each side. Drain them on paper towels. Add another 1/2 cup of oil to the pan. Fry the remaining eggplant slices. Drain on paper towels.
In a clean large frying pan, heat 3 tablespoons of oil and saute the onion until soft, about 15 minutes.
Preheat the oven to 350 degrees F. Arrange the eggplant slices on the bottom of a shallow 9-by-13-inch baking pan. Spoon the Salsa di Pomodoro evenly over the eggplant.
Combine the onion and raisins. Spoon them over the top of the eggplant mixture. Sprinkle lightly with vinegar and mint. Bake for 10 minutes. Remove from the oven, and cover with the cheese slices. Return the pan to the oven and bake until the cheese has melted, about 15 minutes. Remove from the oven and cool. Serve at room temperature.