In a large mixing bowl, combine the sourdough starter, warm water, and olive oil.
Add the flour and salt to the bowl and mix until a shaggy dough forms.
Turn the dough out onto a lightly floured surface and knead for about 8-10 minutes until smooth and elastic.
Place the dough in a lightly oiled bowl, cover with a damp cloth or plastic wrap, and let it rise at room temperature for 3 to 4 hours or until doubled in size.
While the dough is rising, prepare the tomato sauce by mixing crushed tomatoes, dried oregano, dried basil, garlic powder, and 1 tablespoon olive oil in a bowl. Set aside.
Preheat your oven to 425°F (220°C).
Once the dough has risen, lightly oil a 9-inch deep dish pizza pan or cast-iron skillet.
Press the dough evenly into the pan, pushing it up the sides to form a thick crust.
Sprinkle half of the shredded mozzarella cheese evenly over the dough.
Spread the prepared tomato sauce over the cheese layer.
In a medium bowl, toss the sliced onions, bell peppers, mushrooms, and black olives with salt and black pepper.
Distribute the seasoned vegetables evenly over the tomato sauce.
Sprinkle the remaining mozzarella cheese over the vegetables, followed by the grated Parmesan cheese.
Bake the pizza in the preheated oven for 40 to 45 minutes, or until the crust is golden brown and the cheese is bubbly and slightly browned.
Remove the pizza from the oven and let it cool for 10 minutes before slicing and serving.