Boil the potatoes in their skins, peel them and cut them into thin slices. Cut the mushrooms, zucchini, bell pepper and onion into small cubes and fry in a non-oiled pan. Season with salt and pepper. Do not let the vegetables get too soft and fold them into the sliced potatoes while they are still warm.
Cut the feta cheese, ham and herbs into small pieces and add to the potato salad. Pour vinegar and oil over it and season again with a little salt (feta cheese and ham are already very salty) and pepper.
You can also use spring onions instead of an onion. The potato salad tastes best freshly prepared and still lukewarm.