When the potatoes are in the oven, prepare the vegetables. Brush a second baking pan with oil and first add the onions, pepper pieces and mushrooms. Season with salt and pepper, mix everything well. After the potatoes have been baked for 15 minutes, put them in the oven. After another 10 minutes add the zucchini, again after 10 minutes the tomatoes and bake for another 10 minutes. Then everything should be done. Season once more heartily with salt and pepper and sprinkle with the parsley.