So, I’m guessing most French Onion soups you’ve eaten have been the ones with beef stock in them, right? Nothing wrong with those but shouldn’t an onion soup taste like onions? Not beef soup or chicken soup, but onions. I think we have become so conditioned to those flavors in soup we immediately think that’s what soup requires. This soup is the one which turned me on to using water instead of stocks in my soups and it comes from Michael Ruhlman’s Twenty. When you make it you’ll understand why I’ve turned to this technique.
Twenty is all about techniques and ingredients (can you believe 20 of them?). According to Ruhlman, water and onions are two of the most powerful tools a cook has, probably only topped by salt. (Salt, Water, and Onion are three of the first 4 chapters in the book, the first chapter being Think, a novel idea these days…but I digress). Water is pretty obvious because you use it in so many things, but onions? Yes onions, because as Ruhlman says onions have a ‘volume knob’ depending on how you use and cook them. Just think for a second how a burger with raw onion tastes compared to how one with caramelized onion tastes. Veeeery different flavors. Raw, sweated, or caramelized, each way gives the onion different flavor profiles. This French Onion soup showcases the last one, using a technique where you slowly cook down a huge pot of onions into a mass of caramelized sweetness then add water. Voila. Soup is on.
A couple quick notes on this recipe. First and foremost, it takes time. In order to get the awesome sweet flavor of the onions you need to cook them down and slowly cooking down 7-8 pounds of onions cannot be done in an hour, more like five. I know, I know, in the modern world everyone is used to getting things so FAST, who has time for slowly cooking down onions. Well suck it up. Trust me, this winter when you’re all cooped up you’ll have time. The real beauty of this slow cook method is you really don’t even need to stir the onions. Just let them cook. Go in the kitchen every hour or so and give them a quick stir but since they are releasing tons of liquid they won’t burn or stick. Trust me! There is very little active time for you here other than slicing up the onions.
Which brings me to my second note about this recipe. Make sure you get big onions, the bigger the better. Much easier to peel and slice. Which would you rather peel; five or six large Spanish onions or twenty-five of those little yellow onions which come in the bag? Go with the big ones. In the end the soup ends up being well balanced with the additions of salt and vinegar (btw, Acid is Chapter 5 in Twenty).
PS – While getting this post ready I saw a notification from WordPress congratulating me on 3 years. Can’t believe it! Here’s to another great year of delicious food and fun travel, and thank you for reading.
French Onion Soup (adapted from Michael Ruhlman’s Twenty)
- 7-8 lbs Spanish onions, sliced
- 1 Tbs butter
- 3 big 4 finger pinches of salt
- 6 C water
- ¼ dry vermouth
- ¼ C Apple Cider Vinegar
- Comte cheese/Gruyere
- Toasted French bread slices
Melt the butter in a large pot (and I mean LARGE) over medium high heat. Add the sliced onions and salt. Cover the pot and cook onions until they begin to steam and have released some of their water.

Remove top and turn burner down to low. The onions will begin to release a lot (A LOT) of liquid. Taste it, it’s nice and sweet. Let the onions cook on low heat for approximately 5-6 hours. The onions will release all of their liquid, which will then cook off and eventually caramelize the onions.

When the liquid has cooked off and the onions have reached a nice brown color add the water and bring to a boil.

Reduce heat to simmer and stir in the vermouth. Stir in the vinegar a little bit at a time, taste, add more if you like.
Ladle soup into ovenproof bowls, place the crostini on top making a kind of raft, mound the cheese on the crostini, place under broiler in oven until cheese melts and browns.