This stew recipe uses the traditional trio of potatoes, carrots and mushrooms. You can add slightly more or less of the three veggies, depending on which ones you like the most. Other vegetables that are good in stew are chopped tomatoes, rutabaga, turnip, zucchini and green beans. For this recipe, keep in mind that zucchini and green beans cook very quickly in a pressure cooker and will turn out very soft if cooked for 10 minutes.