Preheat oven to 400 degrees. In a large baking dish lined with foil, mix all vegetables with olive oil and salt and pepper. Roast them for 20-25 minutes, or until the veggies have cooked down and are turning golden brown. Roll out the pizza dough (until roughly 12 inches in size) and place on a round pizza stone or round sheet pan. Brush olive oil all over the dough. Sprinkle with oregano. Spread sauce over the dough (using how much sauce you prefer), cover with cheese, and top with roasted veggies. Spread sliced tomatoes over the top. At 400 degrees, bake the pizza for 20 minutes, or until crust is golden brown and cheese is melted. Enjoy!