Interesting. I believe Jacques Pepin used to talk about how the local workers used to have onion soup for breakfast on cold days before heading out. Perhaps it is a regional thing, but I would think you are a better source than I.I'm not knocking any of the advice and ideas expressed here, but why is onion soup always described as being "French"? I have lived in France for 15 years, and have yet to see this item on the menu of any bistrot or restaurant that does not cater exclusively to tourists. I suspect that the attribution is some kind of nostalgic (or perhaps imaginary) invocation of the nights spent roaming Les Halles, when France was a poor country and onion soup was a necessity on the menu. The same applies to vichyssoise - a soup that is unknown to most French people, and snails and frogs legs - shunned by the vast majority.
Every day, on my way back from work, and in the shadow of the Eiffel Tower, I walk past the unspeakble local brasserie where I observe eager tourists scarfing canned onion soup and equally canned snails. It's enough to make me not want my dinner.