Make your dough by mixing the sourdough starter, flour and salt together (adding a bit of flour at a time until it takes shape but is still a little sticky) and knead the dough for about 30 seconds.
Place the dough in lightly floured bowl and cover with a towel, set aside for 1 hour. (The pizza steel or stone needs to preheat for 1 hour as well, so preheat oven to 550 degrees after you finish making your pizza dough)
Prosciutto wrapped Apples (5 min.)
Cut apple into thin slices. Cut prosciutto in half, lengthwise. Wrap apples slices with prosciutto for a total of 16 prosciutto wrapped apples.
Balsamic Aioli (45 min.)
Cut top off of garlic and discard top, then add oil, salt and pepper to garlic. Bake in oven at 420 degrees F° for 30-40 minutes. Remove from oven and let cool, then squeeze out the roasted garlic cloves (remove any garlic peel) chop, and set aside roasted garlic.
Mix together mayonnaise, balsamic vinegar, roasted garlic, salt and peeper, then set aside.
Balsamic Reduction (10-15 min.)
Over medium heat bring bring balsamic vinegar to boil, reduce heat to med-low and cook until desired consistency, remove from stove and let cool slightly, then carefully pour into a microwavable container. Set aside.
PIZZA (8-10 minutes)
Preheat oven to 550 degrees F. with baking steel or pizza stone inside the oven for 1 hour.
Cut brie into thin strips, then cut strips into thirds, removing excess rind. Grate mozzarella.
Flour surface and roll out the dough. Put a floured pizza peel underneath the dough. Add sauce, cheese, and toppings. Pat down the toppings before putting into the oven.
Bake pizza in the oven at 550 degrees F. for 8-10 minutes.
Remove pizza from oven with pizza peel and let cool for 5 minutes.
Drizzle balsamic reduction over pizza (if the balsamic reduction is too thick, microwave it for 10-15 seconds).