1.Preheat A Skillet Over Medium-Low Heat. 2.Sprinkle Cut Sides Of Roll With Balsamic Vinegar. Layer One Slice Of Mozzarella Cheese, Tomato Slices, Basil Leaves, And The Remaining Slice Of Mozzarella Cheese On The Roll. Close Sandwich; Rub Outside With Olive Oil. 3.Place Sandwich In Preheated Skillet; Top With Another Heavy Skillet To Press. Cook Until Bread Is Toasted And Golden, About 3 Minutes. Flip Sandwich; Top With Skillet. Cook Second Side Until Toasted, About An Additional 2 Minutes.