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Jan 11, 2010 05:39 AM

Why Didn't My Onions Carmelize?

I tried and failed to carmelize onions last night. Why didn't they brown? I followed Julia Child's instructions from The Way to Cook, which has you cook them with the lid on for 10 minutes and then add salt and sugar and cook with the lid off. I used a Le Creuset cast iron pot and it was bubbling evenly across the bottom, meaning that I believed the heat was high enough to produce carmelization but not so high that the onions would burn before carmelizing. I kept at it for about an hour and a quarter but then the onions started to break down and I decided I needed to get on with the second phase of the project or we'd never eat dinner. Any suggestions of what I should have done differently?

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  1. Was there a fair amount of liquid in the pot? Did you use any fat (butter) in the process (just curious.) Moisture in the onions that was released when cooking possibly never evaporated so they could carmelize before they started to break down. Could have been the onions you used, perhaps they were very fresh and had a lot of moisture.
    What Julia had you do was to sweat them, covered, then salt, to draw out moisture and sugar, to faciliate the carmelizing step. The salt and sugar also adds flavor. Nothing wrong with this method and besides, I wouldn't dare criticize Julia Child, she's one of my heros. I wouldn't sweat them with the lid on, however but that's just me.
    Yellow onions are best, IMO but people like the sweet varieties, which have lots of sugar, or even reds. Sounds like you got stewed onions, rather than carmelized. The time you spent was significantly longer than it takes to complete the normal carmelization process BUT it depends on the moisture in the onion. Sometimes it can take quite a while for the moisture to evaporate and browing to start.
    If there was a significant amount of liquid in the onions, you can strain out the liquid and continue with the process. If you try this again with the same onions, and find you have a lot of liquid in the pot, try the straining thing.

    5 Replies
    1. re: bushwickgirl

      Yes, I used butter and a bit of oil. I used plain yellow onions, nothing fancy. I bought and cooked them yesterday so they were new to my kitchen but I don't know how long they were in the store. As the cooking process proceeded the liquid definitely reduced and got starchier but they never browned. In fact, at the end of the cooking time the bottom of the pot started to scorch but they still didn't brown.

      1. re: Velda Mae

        You shouldn't have any liquid in the onions to get them to carmelize. A little fat is ok. Maybe you had too much fat. Were you stirring them frequently? If they were starting to scorch on the bottom, they needed to be stirred. Actually, the fact that they started to scorch was an indication that they were going to start to carmelize (the moisture had evaporated) and just needed to be stiired and you needed to turn the heat down a bit to let the carmelizing happen. So you may have been right on the edge of having it work.

        1. re: bushwickgirl

          I doubt it was too much fat; I think the Anthony Bourdain onion soup recipe I made recently called for one and a half sticks of butter, and took time but browned beautifully eventually. I think you're right that the quantity the OP was attempting needed to be turned down, stirred and given time.

          1. re: mcf

            I used 1 1/2 tablespoons of butter and 1 tablespoon of oil for 2 1/2# of onions. I did stir frequently throughout the process.

            1. re: Velda Mae

              I think they needed time, is all, then. My big pot of onions took forever in Le Creuset with all that butter, too. I would've needed a commercial stove and ginormous pan to not have them somewhat deep and crowded before they cooked down. Had to stir a lot.

    2. I agree with bushwickgirl that it sounds like a moisture problem. With a high-sided pot and a LOT of onions, you might have not got the needed evaporation. You tell of the "bubbling" in the pot, which makes me wonder. When I do this process, the sound is really more like a very slight sizzle, and the onions should be good to go in 40-60 minutes max.

      1. You needed a shallower pan with a wide bottom. You had too thick a layer of onions for that style of pot. Also, if you slice crosswise the onions will break down faster than if you slice from pole to pole. If you freeze sliced onions first, they will cook faster than freshly chopped, as long as you break op the frozen clumps. Freezing breaks down the cell walls so the liquid evaporates faster.

        2 Replies
        1. re: greygarious

          Carmelizing onions is not having them break down; that's not the effect you want. Soften considerably and carmelize, yes, but not break down. I define "break down" as fall apart, a problem the OP had and didn't want.
          "Freezing breaks down the cell walls so the liquid evaporates faster." Do you mean that the liquid in the onion will be released faster because they've been frozen and the cell walls have ruptured?
          I agree that possibly the OP may have started with too many onions in the pot but even so they will eventually reach carmelization. I think the OP just didn't cook them long enough.

          1. re: bushwickgirl

            I didn't intend to suggest that the onions need to fall apart - that's why I mentioned slicing them from pole to pole instead of crosswise. Yes, the onion liquid releases and evaporates faster if the sliced onions are frozen - I discovered that serendipitously but of course it makes sense, just like some people make stuffed cabbage by freezing the head rather than boiling it. When I do caramelized onions, it's 5# at a time, and I don't freeze them first, because I rarely have that much free space in the freezer. If I am doing a cooking marathon I sometimes prep too much onion, which is how I wound up freezing a baggie-ful and later discovering how much faster they cooked. I am retired now so am less pressed for time and don't use that shortcut as often. If I have fresh onions around too long and they start to sprout or spoil, I prep and freeze to save the still-good ones.

        2. I disagree with some of the other posters. It simply takes time - a lot of time. Thomas Keller suggests 5 hours of low heat to properly caramelize a lot of onions.

          For instance, in Bouchon, he has a recipe for onion soup... it's basically 1 stick of butter, a dash of salt, 7 quarts of onions and 5 hours of low heat.

          1 Reply
          1. re: tzakiel

            I would think 7 quarts of onions would take 5 hours at low heat, the operative word here being low heat. I've carmelized gallons of onions and yes, it takes time. I don't think any of the posters here suggested otherwise.
            The time it takes to achieve carmelization depends on a number of variables. It's not a thing, as with most cooking, that you can put a number of hours or minutes on, rather, it's done when it's done.

            Without being presumptive, I doubt the OP was cooking 7 quarts of onions.

          2. Agreeing with both grey and tz, to get a true and *even* caramelization, it's the same theory as good bbq - low and slow. This is why I always "go out" when I get a craving of onion soup. I simply don't have the patience to make it from scratch.

            I also agree that the onions need to be, as much as possible, in a single layer across the bottom of the pan. If they're layered up, they will steam rather that brown. Same theory as crowding too much meat/ground beef in a pan to sear.

            To "brown" them (say for spaghetti sauce or chili) still takes mine about 30 minutes on average and even those, I stay just under a medium temp. Even with that, the browning isn't completely even across all of the onions, but since they're not the visual "star" of the dish, I don't really care. (All-Clad stainless)