1 large eggplant (cut lengthwise into 1/4-inch-thick slices, peeling optional)
  Salt and fresh ground black pepper
1/4 cup olive oil
4 ciabatta or francese rolls (split in half)
1/4 cup pesto
1 large ripe tomato (thinly sliced)
1 ball (8 ounces) fresh milk mozzarella or mozzarella di bufala (cut into 8 slices)