BALSAMIC GLAZE: In a small saucepan heat balsamic vinegar, ½ cup water, and brown sugar until boiling. Whisk 1 Tbsp COLD water with the cornstarch in a small bowl to make a slurry. Once balsamic mixture is boiling add slurry and whisk until it's thick and glossy. Remove from heat and set aside to cool. (Store this mixture in the refrigerator.)
*Place frozen dough on a greased baking sheet. Cover with sprayed plastic wrap and let thaw at room temperature for 4-5 hours.
Cut dough in half. Roll each piece of dough into a circle. Use a little flour to keep it from sticking, if needed.
Place 2 Tbsp of olive oil in a bowl for brushing the dough, and the other 4 Tbsp in another bowl with the minced garlic.
Preheat a gas grill until nice and hot, then turn the heat down as low as it will go.
Brush oil on one side of each dough. Place the oil-side-down onto the grill. Cook for 2-3 minutes, checking for the dough to look puffed, and golden brown on the bottom. Lightly brush the top side of each dough with oil, and flip it over.
Divide the olive oil + garlic mixture between the two flatbreads. Spread evenly. Season with salt and pepper. Top with slices of fresh mozzarella and tomatoes. Close lid and let cheese melt slightly. (Watch the cook on the bottom of the crust so it doesn't burn. Heat should be as LOW as it goes.)
Remove flatbreads from grill and top with freshly sliced basil and drizzle with balsamic glaze. Slice and enjoy immediately.
*TIP FOR THAWING: If you plan ahead, you can pull the frozen loaf the night before and keep it in the refrigerator until ready to use the next day.