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Feb 16, 2014 04:49 PM

What is the best thickener for GF onion soup?

I am using Julia's recipe with a gratinee of Gruyere cheese. It needs to be gluten free.

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    1. Dehydrated potato flakes. They dissolve and add zero other flavor. Look for instant mashed potatoes with ONLY ingredient of potatoes, do not boil. Might be $2.

      1. I don't know if I'm too late with my answer but I'd use pureed caramelized onions to thicken the soup; you're already using them, just make extra

        20 Replies
        1. re: Cherylptw

          I want to keep with the same ratio of flavors as in the recipe.

          1. re: wekick

            Well, you got two gluten issues at hand. Thickener and the baguette/bread toasted slice.

            If going natural, I say white rice flour or the dehydrated potato flakes to facsimilate the roux factor the flour adds.

            Some up front at end of onion carmelization as usual and then observe after half cook time with broth.

            Neither of the above will affect flavor from orig recipe in my eyes, but you may need to push and pull to get thickening.

            As for your toasted bread choice, I'll await news of what you chose at serving time. :-)

            1. re: jjjrfoodie

              My DIL has GF baguettes that are not bad. We are making this for a birthday party.

              1. re: jjjrfoodie

                I have eaten many French onion soups both made by me and at restaurants. Who is serving thickened French onion soup? It is usually a rich beef booze herb enhanced broth with long sumptuous strands of caramelized onions covered in a crispy toast and cheeses melted under the broiler. I am seriously confused.

                1. re: MamasCooking

                  Evidently Julia Child did. No need to be confused. There are all kinds of onion soup and yes Julia Child put a little flour in hers. We are not talking thick like pea soup but body. I would be alarmed if mine came with melted cheeses. It has to be brown and bubbly on top and something like gruyere. I ask and if it's just melted cheese, no thank you, if I am in a restaurant.

                  1. re: wekick

                    Cheese melted under a broiler = browned/bubbly. Traditional.

                    1. re: wekick

                      I suspect Julia adapted her recipe with a memory of the Lyonnaise-style of onion soup, which is somewhat thicker (though with a liaison of egg yolks).

                      1. re: wekick

                        Yes. Recipes that call for flour (and many do) use about a tablespoon sprinkled in with the onions.

                        It is not overtly thickened like gravy or a cream soup.

                        But like I said before, the flour is not necessary.

                        1. re: C. Hamster

                          Julia uses 3 tablespoons of butter browned flour.


                          I don't use flour in mine, either. I don't find any reason to dilute the flavor of the onions with a thickener. It's plenty rich the way it is.

                          By the way, I love how she recommends topping the gratinee with a combination of shredded swiss and parmesan cheeses, which is obviously a reflection of the bland state of cheese in America at the time these shows were filmed. I'd feel very comfortable adapting the recipe using a proper gruyere instead of the bland swiss/green can parmesan that she likely used in her show.


                          Mr Taster

                        2. re: wekick

                          > Evidently Julia Child did. No need to be confused.

                          See my link explaining why you're both right, MamasCooking and wekick.


                          Mr Taster

                        3. re: MamasCooking

                          Me, too. I'd never heard of thickening it, nor would I want to. I make a very beefy broth with roasted bones for it, well reduced, and lots of onions then cheese.

                      2. re: wekick

                        You're going to have the same flavors with pureeing the soup but as many have noted, onion soup is not supposed to be thick. Good luck

                      3. re: Cherylptw

                        that's what I'd do as well: my onion soup contains onions - so many that at first they barely fit into the pot - sauteed long and slow until they're a rich, thick, brown caramelized mass - and stock. The slice of bread is just there to hold up the cheese, and doesn't go on until immediately before serving time, so the soup itself is gluten-free.

                        1. re: tardigrade

                          I don't understand the OP's way of thinking that if part of the soup was pureed with the same onions used anyway, that it would not have the original flavors...any idea? Anyone?

                          1. re: Cherylptw

                            I notice he is avoiding responding to our queries too. Not sure what he is looking for.

                            1. re: Cherylptw

                              The first suggestion was to purée more onions so that would throw the ratios off from the specific recipe I am using. You could purée the soup as a whole but I have done that with some other sauces based on caramelized onions and wasn't that crazy about the taste. I have puréed other soups in the same way that usually had not as many onions and things that were starchy or at least not as flavorful as the onions. They tend to stay balanced. I have had carrots get too strong when puréed in a soup as well.

                              1. re: wekick

                                While I don't like the idea of putting flour in onion soup, I can see not wanting to thicken with pureed onions either.

                                If you use a homemade beef stock made with plenty of bones, cartilage and connective tissue, of the sort that, once cooled, is the consistency of set gelatin, the soup will have plenty of body.

                                If you still want a thickener, I would suggest arrowroot, because it will be neutral-tasting and - this is important, I think - stays clear, so your soup won't be opaque. You would add this at the end of cooking, in a slurry, just like you would cornstarch. Cornstarch added in a slurry at the end would be another option, but arrowroot would be a better choice, I think, for this application.

                                1. re: wekick

                                  We're not talking about carrots but onions which is the only vegetable in a onion soup. The onions are already caramelized so how much stronger can you possibly make them by pureeing. Makes no sense but good luck on that one.

                                  1. re: Cherylptw

                                    Consider that caramelization and pureeing are two entirely different processes. Heating the onion changes the flavor by destroying certain flavor components and removing water and allowing the caramelization of the sugars and the Maillard reaction to take place. Pureeing breaks the onions down into very tiny particles. This allows the flavors to be more efficiently dispersed in the soup making the onion taste stronger. I mentioned carrots as another example of a food that I have noticed can get strong in this way.

                          2. Why would you want to thicken onion soup? Increase the amount of onions if you want more of an onion stew. A traditional onion soup is a broth with onions, no thickeners at all.

                            12 Replies
                            1. re: smtucker

                              This is what I think also. I have never thickened onion soup.

                              1. re: smtucker

                                I am looking to replicate a specific recipe.

                                  1. re: magiesmom

                                    I referred to it in the original post but maybe I should have said "Julia Child's". Here is a link.

                                    1. re: wekick

                                      it really doesn't need flour, or any kind of thickener. it. just. doesn't.

                                      1. re: hotoynoodle

                                        I made Julia's Boca Negra without flour and it came out ok but with a slightly different texture. I might just make a batch of soup and try some of these ideas and some without any thickener and see. As daislander said, it might be about mouthfeel or it might not make a difference at all. I used to work in a food lab and mouthfeel is a big deal for some people.

                                        1. re: wekick

                                          Onion soup doesn't need flour IMO.

                                          1. re: wekick

                                            mouthfeel is a big deal for me. :)

                                            starting with a rich, gelatinous stock will give you a much rounder, but cleaner, mouthfeel than a few spoons of flour.

                                            now that i see the link, it's from julia's old show -- from the 60s? not too many people use flour in a soup like this anymore.

                                            1. re: hotoynoodle

                                              She never changed the recipe much and it is on her later shows as well. It has stood the test of time and it is lauded on many forums and blogs. I can't say what many people do in their kitchens anymore but you find recipes with and without flour. I always have a hard time sticking with a recipe but am trying to do so here. The first reason is because I have heard so many praise her recipe. The second is because we had a department store, now closed that was famous for its onion soup and the recipe is almost the same as Julia's. Everybody at our little gathering has fond memories of that soup.

                                  2. re: smtucker

                                    I'm not looking for what is traditional but what I like. A little body.

                                    1. re: wekick

                                      A rich beef stock has tons of body.

                                      It seems to me that when a recipe exists without gluten and is wonderful it is silly to use one that has gluten.
                                      The best GF foods are without gluten inherently.

                                    2. re: smtucker

                                      I'd usually add a very very small amount of Plain flour to add a bit of body. but will also add a tiny bit of Xanthan at the end to make it more feel more richer.

                                      1. re: sal_acid

                                        I bought a bag from Red Mills a while back and have found it to be an excellent thickener as well as stabilizer. It takes so little to do the job for most things and imparts no flavor of it's own. It's heat stable and will not loose it's thickening ability the long it's cooked.

                                        1. re: scubadoo97

                                          It's also a laxative, which many people surely need, but some of us do not need.

                                          1. re: MelMM

                                            At that low a dose I doubt it would be noticed by even the most sensitive

                                            1. re: scubadoo97

                                              You would be surprised. It doesn't take much xanthan gum to thicken something, and likewise, it takes very, very little to have a laxative effect. The amounts in a bottled salad dressing, for example, are well beyond the threshold.

                                            2. re: MelMM

                                              Lots of ingredients act as a laxative in certain people, like the pound of cheese used to put on top of the soup in this recipe.

                                              1. re: Cherylptw

                                                Xanthan gum is used in medicine as a laxative.

                                                1. re: MelMM

                                                  Not very commonly used in medicine. Which laxative are you talking about? Not an ingredient in most OTC preps. that I've run across.

                                                  It's most common use is a thickener and emulsifier. And used a lot in GF baking.

                                                  1. re: scubadoo97

                                                    I don't know about specific OTC laxatives (if any) that it might be in, because I do not ever take a laxative.



                                                    On that last link, click through to see tabs for "uses" and "side effects".

                                                    For me personally, xanthan gum at the levels found in bottled salad dressing and in gluten-free baked goods is sufficient for me to experience the "side effects". I have been gluten-free for 13 years, and I've had plenty of time to do controlled experiments on myself. There might be a lot of people (perhaps a majority in the US) who can benefit from this laxative effect, but for others, it is nothing but trouble.