Dice the potatoes and carrots. Cut the zucchini and onion into very large cubes, cut the meat into strips.
Heat the oil in a large saucepan to the smoke point. Sear the strips of meat and remove them from the pan. Season with salt and pepper. Fry the onions, carrots and zucchini in a saucepan. Deglaze with cold broth and add the potatoes. Season with the spices (except mustard). Add the meat and cook everything until soft for 30-40 minutes. Then remove some of the vegetables with the stock, puree and add again. That makes the stew creamy.
Before serving, add a little mustard and season again to taste.