In most instances, you will need to rehydrate your dried black trumpet mushrooms by immersing them in liquid for 20-30 minutes, but they can be used dried in some cases (if they will be cooked in liquid or ground to use as a seasoning). Once rehydrated, use your black trumpet mushrooms as you would a fresh mushroom. Dried black trumpet mushrooms are a great addition to many types of recipes. We especially love them in rice and pasta dishes, but they are also great in soups, sauces, and on pizza. Here are some suggestions for using dried black trumpet mushrooms in your cooking and an incredible recipe round-up (including the most delicious mushroom pâté.