Sauté onions and celery in a little oil in six-quart pot.

Add whole parsnip, carrots, and zucchini. Add barley, split peas, can of drained mushrooms, salt, and enough water to fill pot three-fourths full. Bring to a boil and cook about one and a half hours or until carrots are soft.

Remove carrots from pot and set aside. Using a hand blender, blend vegetables in pot until smooth or desired consistency. Slice carrots into thin rounds, return to pot, and simmer an additional 10 minutes.