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Nov 13, 2010 01:34 PM

Crock pot French Onion Soup - Caramelize onions first, then add stock?

So, I'm thinking of making French Onion Soup, and I've seen lots of posts on using a crock pot (or oven) to caramelize the onions (I'm doing a double batch of soup, and don't have a saute pan big enough for 4 lbs of onions).

Based on other posts, I'm thinking I can put the onions in my crock pot overnight on low, and get them to caramelize, then tomorrow, put them in a pot with the broth & seasoning and simmer for an hour or so and then top with the cheese and voila - dinner.

I've seen crock pot soup recipes that put the broth in with the onions, but I would think that they wouldn't caramelize as nicely. I guess I could just add the broth AFTER they are done caramelizing, and keep it all in the crock pot too. Anyone have good results with FOS and a crock pot.

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    1. I've had mixed results caramelizing them in my crockpot, mostly not so good. Stovetop is the way to go for that step. And I'm a big believer in my slow cooker - my most beloved kitchen multitasker.
      However for simmering the onions and broth together the pot is perfect! Frees up the stovetop, it's low maintenance and doesn't heat up the kitchen. But you'll probably need more than an hour.

      1. I don't have my crockpot here so I can't test this out. But as far as I remember, I had to crack the lid so the onions didn't end up swimming in liquid. But then you have to take a look at it once in awhile to make sure it's not getting TOO dry. I'm not sure I'd try to do it overnight. I think I HAVE done it overnight but I don't remember what result I got. Can't remember if that was with the lid cracked or not.

        1. I used to do it, a pot full of onions and a stick of butter. But, greygarious said it turns more into cooked onions, not caramelized so I compared them and doing it on the stove makes much better caramelized onions. That said, I think it would be fine to make the french onion soup in the crockpot, after caramelizing the onions, whichever way you choose. I would not just put the raw onions in with the broth, though.

          1. I just did it successfully - with a combo method.

            I cooked three and a half pounds of sliced onion in my crockpot - on high - for 10 hours. They got to a lovely light brown, with a TINY bit of liquid. Threw them in the fridge and the next day, put them in a stock pot and reduced them/browned them a bit more, over a higher direct heat. It took maybe 15 minutes. Then I added my broth, wine and seasonings (doing Ruhlman's veggie onion soup) and simmered it for 10 more minutes.


            A nice depth of flavor from the long cooking but, so so easy as I had to stir the crockpot maybe 4 times in passing. Give it a try!

            3 Replies
            1. re: happybaker

              It's cool that you got good results that way happybaker. The only other option I can think of is to get all of your sautee pans going at the same time and do them in batches. You can crowd a little bit with onions but not too much. Your way sounds much more hands off, which can be great.

              1. re: nihongojoe

                I would think putting sliced onions in a crock pot to "carmelize" overnight would be to steam the onions probably turning them to mush.
                I cook the onions for onion soup sliced up and put them in batches in a Dutch oven. You can also do the same in a sautee pan but I like to use one pot for as many dishes as possible.
                As I cook the sliced onions and set the carmelized aside and cook the next batch. Doing them in batches gives them space and keeps them from steaming.

              2. re: happybaker

                i did a very abbreviated version of this. i put them in the crock pot for about 5 hours last night. they were already a very light brown (on low most of that time, on high for maybe 1 hour) let them cool, put them in the fridge. this evening, drained them a bit, put them in a pan with butter, on high to medium-high, and caramelized them in about 15 minutes. perfectly sweet and soft but not total mush. made the best french onion soup with them i've had in ages.