Combine first four ingredients in a non-reactive baking dish (glass, corningware - not metal), and roast, stirring several times, for 45 minutes.
Meanwhile, combine next three ingredients in a covered baking dish, and roast for 30 minutes, stirring twice.
Deglaze onions with wine.
Melt butter in soup pot, add chopped onions and celery, and sweat until onions are translucent. Add roasted onions, mushrooms, stock, and soy sauce, and simmer 30 minutes, adding additional soy sauce if necessary.