In a large stockpot, sauté the parsnips, mushrooms, and onion in oil until the onions are translucent.
Add all other ingredients to the pot and gently boil (at a strong simmer) until everything is cooked through, particularly the parsnips. (About 30-40 minutes)
Season with salt and black pepper to taste and serve.
Notes
Please note that the nutrition data given here is a ballpark figure. Exact data is not possible.