Tomato and Tapenade Tartlets

Basil, small fresh leaves

Tomatoes, ripe medium

Balsamic vinegar

Green or black olives, pitted

Or black-olive tapenade, green

Fleur de sel or coarse kosher salt

Olive oil, Extra-virgin

sheets 1 17.3-ounce package frozen puff pastry, frozen

Mozzarella cheese, fresh