Fold one basil leaf in half, dark side facing out, and add it to the skewer. Add one mini-Mozzarella ball, followed by another folded basil leaf, and another tomato.
Repeat Step #1 with the remaining tomatoes, basil, and Mozzarella until you have 16 completed skewers.
Arrange on a serving platter and set aside.
To prepare the glaze, add balsamic vinegar to a small sauté pan over medium-high heat. Cook, stirring frequently, until the vinegar is reduced to about ⅓ of its original volume.
Remove glaze from heat and let cool slightly. Drizzle over the skewers, along with some extra virgin olive oil, if desired.
Serve immediately.
Notes
Tip: If you're having a hard time finding fresh basil in your local grocery store, look for the "living herb plants" that most establishments are now selling. You can prepare these ahead of time! Prepare according to directions, only do not drizzle the balsamic glaze on top. Wrap the skewers with plastic wrap and store in the refrigerator. Right before serving, warm up the glaze and drizzle on top.