2. Assemble Ingredients
Combine the the mushrooms, carrots, celery, onions, fennel, parsley, and thyme in a 7 ½-quart (7L) stockpot. The pot should be quite full with vegetables; if you can't quite fit everything in, that's okay. Simply save any extras for another use or compost.
Cover the vegetables with the water. Insert the probe, taking care that it is not touching the bottom of the pot. Wrap the cord around the pot's handle to keep the probe in place.