Make tart: Put dry ingredients into food processor & mix. Add butter and mix until like pebbles. Add water, slowly until dough ball forms. Turn out onto board, and knead a few times. Pat into disk and refrigerate for one hour. Roll out 1/8-inch thick into an 11- or 12-inch circle, and press into 9-10 inch tart pan. Pierce bottom with fork tines, to prevent puffing while baking. Filling: Whisk together Balsamic and mustard. Brush onto the bottom of tart. Place the mozzarella, spreading evenly all around bottom. Lay the Tomatoes down, overlapping, in a circular pattern, starting from the outer edge, and ending in the center. You should have 2-3 rows when finished. Sprinkle herbs and garlic all over, drizzle with olive oil. Bake in preheated 400 degree oven for 35-40 minutes.