This flavorful flatbread is pizza-esque, but doesn't require any cheese! If you have salt-free Italian seasoning on hand, you can use ¾ teaspoon in place of the oregano, thyme, and basil.
To make the dough, in a mixing bowl, whisk together the whole-wheat flour, ½ cup all-purpose flour, yeast, and salt. Add the water and oil. Beat with a mixer until smooth.
Stir in the remaining all-purpose flour to form soft dough.
Turn the dough out onto a floured surface and knead by hand until consistent and elastic, about 4 minutes. Cover and let stand for 15 minutes.
To make the topping, in a large bowl, stir together the mushrooms, tomatoes, green bell pepper, olives, onion, oil, vinegar, salt, pepper, oregano, thyme, basil and garlic powder.