HOME > Chowhound > Home Cooking >


Slicing Onions for Onion Soup

When slicing onions for making onion soup, how should the onions be sliced -- pole to pole or crosswise? In the past, I've used the slicing disk of my food processor to slice the onions crosswise. But now I'm thinking this might be a mistake -- that they'll have better consistency, and maybe even taste better after caramelization if I slice them lengthwise, pole to pole. What are your thoughts?

  1. Click to Upload a photo (10 MB limit)
  1. I slice onions the normal professional way: halve them vertically (pole to pole), so you have the root end to keep each half together, then make 3+ slightly incomplete horizontal slices parallel to the cut end on the board, then slice vertically perpendicular to the pole-pole axis, as it were. Chopping involves an intermediate set of vertical slices parallel to the pole to pole axis.

    To tame the power of onions that will be eaten *raw* (it wouldn't matter for cooked slices), I normally just rinse them well in cold water, but Cooks Illustrated explains the following in their Jul-Aug '09 issue:

    "The onions sliced pole to pole were clearly less pungent in taste and odor than those cut along the equator. Here's why: The intense flavor and acrid odor of onions are caused by substances called thiosulfinates, created when enzymes known as allinases contained in the onion's cells interact with proteins that are also present in the vegetable. These reactions take place only when the onion's cells are ruptured and release the strong-smelling enzymes. Cutting with the grain ruptures fewer cells than cutting against the grain, leading to the release of fewer allinases and the creation of fewer thiosulfinates."

    2 Replies
    1. re: Karl S

      Karl, Cooks Illustrated disagrees with you. In their French Onion Soup recipe (Jan/Feb 2008), they made a point of specifying pole-to-pole slicing: "Slicing against the grain results in cooked onions with a lifeless, stringy texture. Onions that are cut pole to pole maintain their shape during our Best French Onion Soup's (page 13) long cooking process." In that version, they call for yellow onions whereas their initial recipe (Jan/Feb 1999) found them "only mildly flavorful", instead specifying red onions because they are "intensely onion-y, sweet but not cloying, with subtle complexity and nuance." A splash of balsamic vinegar was included at the end to restor the color to the red onions, which turn gray during long cooking.

      1. re: greygarious

        Oh, yes, now I recall that. Thanks for the additional information. I do remember the red onion advice, which is what Alton Brown also recommends. Alton Brown also has the single best method for making FOS: using a large rectangular electric skillet (the kind that were fasiononable in the '70s, but are still available at modest procies) to caramelize. I've even taken this inspiration to make FOS in my smaller electric fondue pots when I am making smaller quantities.

      1. re: todao

        The process of caramelizing the onions in that recipe seems so long and labor intensive as compared to doing it all on the stovetop. Have you tried it? Is the end result noticeably better?

        1. re: CindyJ

          I've made this CI soup twice. Long-yes. Labor intensive-not at all. And just about guaranteed not to scorch the onions.

      2. I recall being told at cooking school specifically to cut onions pole to pole for soup. They keep they shape better.

        1. pole to pole, avoids that stringy-ness

          FYI- i've found that i tear up less when i slice onions wearing my contacts as opposed to my glasses

          1. Thanks to all who validated my hunch. Pole to pole it is!

            1. jfood does not mean to confuse the issue but he sat back one day to think about the pluses and minuses of the end product. One of the items that drove jfood crazy was the dangling onions on the sppon. To solve this issue jfood first cuts the onion onthe rquator and the cuts in half. He then slices so that he has semi circles to start the caramelization process. And that process takes at least 3 hours in jfood's opinion for a great onion soup. The first hour to remove the liquid, the second hour to reduce and the third to turn into sugary goodness.

              3 Replies
              1. re: jfood

                Jfood - i figured you'd chime in because I know you love onion soup as much as I do, but exactly how do you carmelize anything for 3 hours? Please explain that process.

                1. re: southernitalian

                  food uses between 6-8# of onions. He uses a large soup pot and the sliced onions normal fill the entire inside of the pot. Heat on medium since he wants to start eliminatingthe moisture in the onions. He stirs every five minutes or so and then you start seeing the steam start to rise violently from the pot. The medium-low to medium heat setting usually bring most if not all of the moisture out of theonions in about 60 minutes, he kids you not.

                  Then the slow is better begings over a low flame. Jfood sets the timer at five minutes has a seat, rises and stirs. This continues for about 1.5 hours. The secret is just keeping the flame low so as not to scorch any onions. The last 30 minutes is almost a constant watch and stir as required. On a snowy day a few years ago jfood actually caramelized the onions for over 4 hours and the results were fantastic.

                  It is a heck of a lot of work, but the medium brown goodness that comes out of the onions, the wonerful creamy texture and the aroma that fils the house is well worth the effort.

                  Once completed please use some good gruyere as well. In jfood's neighborhood the price has approached $25/pound but the difference makes a great dish into a super great dish.

                  Hope this helps.

                  1. re: jfood

                    I do pretty much the same timing and haven't made FOS in a couple of years - I will try the oven method so as not to be so tightly tethered to the stove. Jfood, years ago I used to regularly poach whole turkeys until the meat fell off the bones, then strain, debone, and feed the meat to the pets. (Eventually i realized that this made really moist meat and would remove a thigh and half the breast when just-cooked, using those for people food. The broth became soup but it's so low-fat (and lacking in gelatin) that it was not as good as chicken for noodle or vegetable soups. However, if I added some beef base it made wonderful FOS soup. It's high time to do that again!