A year and and a half ago I was asked to help caterer in a small way for my brother's wedding. His wife is from Brittany and she wanted French Onion soup to serve in the evening of the wedding party, as it is traditional to serve it early in the morning at French weddings which tend to run on through the night.
This soup recipe below is a special one from the bride as she is vegetarian so the usual beef stock is not added here.
I have to admit I would add beef stock and brandy when I usually make French onion soup and that when I have made again it as per the recipe below that I have added marmite to the mixture to get it a little darker. However the recipe above does make very nice soup! I would also serve it slightly differently at home by placing slices of toasted baguette with melted gruyere cheese perched like a lid on the bowl of soup.
In the end my Mum, sister and I made litres and litres of this soup which proved to be a really delicious thing to have later on in the evening at the wedding - tasty and filling but not heavy. We are travelling to celebrate the non-religious Christening of my niece in Brittany soon, I wonder if there will be any Breton Vegetarian French Onion Soup to enjoy at this celebration?
Breton Bride's Soupe à l’oignon recipe (with my notes in red)