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Feb 14, 2007 05:56 AM

Slow cooker caramelized onion question

I am caramelizing onions in the crockpot for the first time, which I am sure will be a life-changing event.

Any recommendations on the best way to get them nice and dry after cooking so they are suitable to use as a pizza topping. Draining in a colander I'm sure will help, but could I run a batch under the broiler, or will that just scorch them? Or perhaps heat a batch in a dry skillet? Roast in the oven?


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  1. jono37, I would think that the onions would come out stewed and watery, rather than caramelized. Just wondering why you're planning to do this in the crockpot, and for how long? If it's just for pizza topping, doing it on the stovetop is not terribly time-consuming.

    On another note, I believe that crock pots must be filled to a minimum level, which I'm sure is over the half mark, if not closer to two-thirds. Check your owner's manual.

    1 Reply
    1. re: FlavoursGal

      I was really excited about the convenience of leaving a huge batch of onions in the crockpot and finding them deeply caramelized without any stirring or supervision when I got back home. If there is no way to get them less "stewed and watery" I will probably go back to the stovetop method. Although I've also heard there is a lower-maintenance oven method.

    2. I also have onions on the go (for the first time!) today. If I wanted to dry them out, I'd probably stick them in a dry skillet.

      I figure if mine don't work out, at least I can cut up my remaining two onions and do it the old fashioned way. :)

      1. They discuss carmelizing onions in a slow cooker and also in the oven in this thread for french onion soup:

        1. I caramelize onions in the crockpot regularly ever since I read about it on this board. I slice up as many onions as the crockpot will hold - for ours, that's about 5lbs. Throw in a stick of butter on top and set the cooker on high. The onions render a lot of fluid in the first few hours. Keep the cooker on high until the fluid has evaporated, then turn it to low and let it cook slowly. The onions gradually brown in the butter. The whole process takes around 8-12 hours for me, but this probably depends on the onions and your crockpot. When it's finished, the onions are caramelized and there's no liquid. The 5 lbs cook down to about a quart which we use on sandwiches and pizza. They'll keep in the refrigerator for months, though ours never last that long.

          10 Replies
          1. re: cheryl_h

            Everything she just said- it works beautifully and I wouldn't think you would need to dry them out.

            1. re: Katie Nell

              So the excess liquid evaporates, even with the lid on the crock?

              1. re: doctor_mama

                Sorry, that wasn't clear in my post. I crack the lid open a little so the liquid can evaporate. Once it's gone, I replace the lid.

                1. re: doctor_mama

                  Yep, there was no excess liquid when I did it, just pretty caramelized onions. I think when I did it, I sliced 6 onions and had about 4 T. of butter and that was it. I was really amazed that it worked so well.

              2. re: cheryl_h

                how long does it keep and how do you store them? I have a hankering now.

                1. re: lbs

                  I don't know how long it keeps before it goes bad. We've had them for at least a month and they were fine. I've heard others say it will keep for months but they don't last that long here. Nothing special about storage - I just put them into a plastic container and put it in the fridge.

                  1. re: lbs

                    I flatten my out in a freezer bag, then just break off what I need. They freeze forever.

                  2. re: cheryl_h

                    It does work, however when I use them I usually just use a pan. I don't use that much that often. However, the crock does work but it took around 7-8 hours for me. For this simple dish I would use a pan but if you need a lot of onions, why not. Nicely brown. But for me. You still need to be around to turn it down at one point and you do need to stir a couple of times. So why not 20 minutes in a pan?

                    Don't get me wrong I love the crock for some things, but for this I wouldn't use it.

                    1. re: kchurchill5

                      When I do this in the crockpot, I never stir.

                      1. re: pikawicca

                        The first time I tried it I didn't stir and they were done but the top didn't caramelize. The second time I stirred a couple of times and it worked. However every crock pot cooks at different heat levels and different sizes too.

                        I first tried this when I was making a large amount of onion soup for a party and it worked ok, but the second time also for french soup for a crowd I tried the stirring and presto. But honestly, I just use a pan now, but I also haven't needed that many onions.

                  3. Well, here's my report. I filled the entire crockpot with sliced onions, added a stick of butter on top, and threw in some salt, black pepper, a dash of olive oil, and a little balsamic vinegar. Cooked on low, covered for about 18 hours, then took the lid off and cooked on high for another two. Wetness was not really a problem; I could just pop some onions in a strainer and they became plenty dry enough for pizza.

                    I'd give the technique an A+ for convenience, but only a B for flavor. I think that you lose something by caramelizing the onions in ceramic over low heat vs. a skillet; the contact of the onions with the hot surface of the skillet seems to my taste buds to sear in a richer, sweeter flavor, whereas the crockpot-cooked onions had a slightly washed-out flavor. Overall, though, not bad at all, and I'm sure I will use this technique again on occasion.

                    Thanks for all the suggestions.