Place baking stone in oven and preheat oven to 375F.
In a medium bowl combine flour, water, olive oil and salt. Mix until batter is uniform with no lumps.
Pour batter on a piece of parchment. Using the back of a spoon, spread batter into an 8-inch circle.
Remove baking stone from oven. Transfer parchment sheet to baking stone, then return to oven and bake for 20 minutes or until crisp on edges.
Remove baking stone from oven. Flip crust on parchment, then top with tomato sauce, cheese, zucchini and caramelized onion. Season with salt and pepper.
Return pizza topped baking stone to oven and bake an additional 10 minutes, or until cheese is golden and edges are crisp.