In a large pot over medium heat, sauté shallots and ginger in oil for 5 minutes. Add parsnips, rutabagas, turnips, potatoes, fennel, and cinnamon stick. Add enough stock to cover the vegetables. Bring to a boil, cover, reduce heat, and simmer 25 minutes. Remove from heat, discard cinnamon stick and puree soup 3 seconds. Season with a few dashes of vinegar. Serve.