11 Mistakes You're Making When Thickening Up Soup

Thin soups, like this pozole verde, may always have their place in your favorite soup rotation. But, sometimes you want something a little thicker — maybe you want to achieve a more substantial mouthfeel or make the meal more filling. Perhaps your recipe calls for a richer soup base than what light broth provides. No matter the reason, thickening up soup is a skill set every home chef needs in their repertoire. But are you thickening your soups correctly? Unfortunately, chances are good you're not. Thankfully, this is easily remedied! 

During my 15+ years in the food industry, I trained dozens of cooks who were just starting their careers. One thing I noticed was that they made some common mistakes when thickening soup, and during my conversations with people outside work, I realized they did, too. So, without further ado, here are 11 mistakes you're probably making when thickening up soup, along with helpful solutions — with these, you'll be making perfect thick soups like a professional in no time.

Liquids are what make your soup, well, soup. But, you should be wary about how much liquid you add in the beginning because too much can lead to a less flavorful dish. The perfect amount will depend on what you're trying to achieve, but I personally think it's better to go light in the beginning if you're uncertain. After all, it's much easier to add liquid than it is to take away.

Allowing your soup to reduce long enough is also crucial. Reduction is the process of simmering something until some of the liquid has evaporated, leaving behind a thicker, more flavorful base. For soups, I like to bring them to a boil and turn down the heat to simmer for at least fifteen minutes — but that's only a minimum and I'll go longer if I can to achieve an optimal taste profile.

Plus, simmering for a while provides you better judgement on how much thickener is appropriate. Certain ingredients like potatoes, beans, rice, and starchy vegetables will help your soup to thicken naturally as they release starches during the cooking process. This will continue even after it's served, so forgetting to simmer may lead to unintentional over-thickening.

A slurry is a combination of a starch and a cold liquid commonly used to thicken soups, as well as stews, sauces, and gravies. The most common option is to combine cornstarch with cold water for a silky, glossy finish with light to medium thickening. However, this is far from your only option.

Each starch adds something unique to a dish, so I recommend experimenting with each of them. For example, arrowroot powder is very similar to cornstarch, except it results in a slightly clearer, lighter finish. If you're looking for a thicker soup, all-purpose flour or potato starch is an excellent option. Use all-purpose flour for a darker profile, and potato starch for a lighter one. 

Tapioca is also good for clear, thick broths, but adds the slightest sweetness to your dish. Rice flour is a common ingredient in gluten free soups that doesn't have much flavor on its own and provides very low thickening. However, you can use quite a bit of rice flour in your soup without affecting the taste, so its abilities can be built upon.

When using a thickening agent, avoid adding it straight to the hot pot of soup because this will cause clumps to form that are challenging to get out. I can always tell when someone hasn't pre-mixed their starch because it features an oddly chalky mouthfeel and a mealy taste. The appearance is also telling, as it will have small bits floating at the top of the broth no matter how much you stir.

The correct method is to combine your thickening agent with a cold liquid, in most cases. This creates a slurry you should slowly pour into your soup, stirring constantly to avoid lumps forming. Once your thickener has been fully added to your soup, continue mixing for a minute and then reduce heat to simmer. As a disclaimer, pre-mixing thickeners works for most soups, but there are thickening options you'd add at the beginning or end of your soup-making which use a different combination process.

Just as there are several starches you could use, there are also numerous liquids. Personally, I rarely use standard cold water to mix my thickening agent unless the dish calls for a very light, clear taste and visual profile. Milk can be used for richer, creamier soups like this broccoli and cheddar option. However, if you want something even richer and thicker, use cream instead. Although I've never personally used it for soup, I've seen some people use yogurt to mix their starch to great success.

Broths and stocks are my preferred liquid for soup slurries because they help layer the flavor profile in a subtle yet defining way. I save back a small amount of broth in the beginning to mix with the thickener when setting up my mise en place. Common options include beef, chicken, vegetable, and seafood broths or stocks. Stocks have a more concentrated flavor profile, while broths are a little milder.

Even for the thickest soups, you want to take the addition process slowly. When you add too much thickener at once, it becomes hard to combine and can cause your soup to become too stiff — at the most extreme, your soup may become more like a gravy or pudding, which is hard to fix while retaining your desired flavor.

Once your soup has reached a boil, prepare your slurry or other thickening agent. Add a small amount to the pot, continuing to stir as you do for the smoothest texture. Give it a brief time to thicken, and then check the consistency. Has it reached your desired thickness? If not, repeat the process until it has. Sometimes, you'll find you don't need all of the thickening agent you prepared, and that's fine. This works for any thickeners that are added during the cooking process.

When it comes to thickening soups, most people immediately think of one of three things — a slurry, roux, or beurre manié. But, there are plenty of uncommon thickening alternatives that could be simpler or more effective for certain dishes. Instant mashed potatoes are an excellent example. These small potato flakes can be added straight to hot soup without pre-mixing and quickly dissolve without clumping. I particularly like adding them to my potato soup recipes. Add them slowly and combine well to avoid a grainy mouthfeel.

Tempered eggs are an option that provides a silky finish. They're used in several non-soup dishes (like traditional flan), but Greek Avgolemono is one popular soup example. However, tempering eggs properly can be tricky. A few key things to keep in mind is to use room temperature eggs, add the hot liquid very slowly, and vigorously whisk throughout.

You can puree vegetables or beans to help thicken a soup. I like this option when making a soup based on those ingredients because I can take a little out of the pot with some broth and blend as-is. Add it back and stir for a thicker, flavorful soup. Sour cream and cream cheese can be added straight to soups for a rich dairy base; make sure to cut the cream cheese into chunks before adding to allow for easier melting.

Many people find a roux challenging, but it's actually simple once you get the hang of it. A roux (pronounced "roo") is a combination of equal parts flour and butter that's used to thicken sauces, stews, soups, and similar dishes. Unlike a slurry, which is added during the cooking process, a roux is made in the beginning.

There are different types of roux, named for the final coloring you're looking for — white, blonde, and brown are the most common. The lighter the coloring, the stronger a roux's thickening power is, which is ideal for gravies. But, the darker it is, the more intense the flavor is, making it a good option for medium-thickness soups.

Personally, I like making my roux using meat drippings instead of butter whenever possible. Once I've cooked the soup or stew's meat, I remove from the pot and add my flour to cook. This helps build a layered flavor profile I find offers a more intense taste. While this trick doesn't work with all meats, I suggest trying it next time you cook a soup featuring bacon, ground hamburger, steak, pork chops, sausage, or ground pork.

A beurre manié is similar to a roux, except it's added at the end of cooking rather than the beginning. The term is a French phrase literally meaning "handled butter," and describes a smooth floury paste. This is a less common thickening technique for the home chef, but is often used in professional kitchens.

To create your beurre manié, place equal parts flour and softened butter into a bowl or on a plate. Gently knead the mixture with clean hands until you have a smooth paste that easily holds its shape when rolled into a ball. If you're gluten-sensitive, you can still add this thickening technique to your repertoire. Just replace your standard flour with a gluten-free option. I've personally used this King Arthur Gluten Free Measure For Measure Flour with great results that taste identical to using standard flour.

Once your soup is almost done, add a small amount of your beurre manié to the pot and stir until combined. I add about a teaspoon and allow the soup time to thicken before adding more. Repeat until you've reached your desired consistency.

Since many thickening techniques use flour, there's a need to cook it for a short time after combining. Raw flour can have a chalky or nutty taste you don't want in your soup, and simmering will get rid of that for you. However, cooking too long after thickening can be problematic because your soup will essentially begin to de-thicken, rendering your efforts wasted. Instead, you want to achieve a delicate timing balance that allows the flour taste to cook out, while also reaching an ideal consistency.

Generally, one to five minutes after thickening is the sweet spot, with some small variation based on the overall weight of your soup — an 8-ounce soup will need less cooking time than a 40-ounce one. Keep in mind that overcooking can also happen if you continue cooking at too high of a temperature. Remember to always reduce heat after adding your thickener. You want a simmer, not a rolling boil.

Understanding your ingredients is your stepping stone to professional soups. But, don't feel overwhelmed — a little research and some experience will make you an ingredient connoisseur in no time. In soups specifically, your ingredients can provide different wanted or unwanted reactions. For example, citrus makes milk curdle, so you don't want to use dairy as a mixing liquid in citrusy soups — milk also curdles if the soup is too hot. Eggs will begin cooking if you add them straight into hot soup.

Of course, it's more than just reactions. You'll also want to understand which broths and stocks pair best with your soup's ingredients. For example, chicken broth can work well for chicken or turkey, while beef broth is generally reserved for soups with steak or ground beef. However, both can work well with vegetable-based soups, while vegetable broth can work well with almost any protein (or no protein at all). Seafood stock is your best option for dishes like clam chowder or lobster bisque.

Mise en place is a French preparation technique used in professional kitchens that means "everything in its place." It's one of the first things aspiring chefs learn because it's so important. Basically, the idea here is that all your ingredients are prepped and on hand before you start cooking — and any tools you'll need should be within reach, too.

For example, if you're making a chicken and sausage gumbo, your mise en place should include the pre-cut meats, pre-measured okra, appropriate seasonings, broth, and everything you need to make your roux, as well as a mixing spoon. When talking about thickening soups specifically, your most basic mise en place will include the thickening agent, liquid, a whisk, and a mixing spoon. 

The reason your mise en place is so important is it helps keep your attention on cooking and avoid certain mistakes — like burning your roux or overboiling your soup while you look for something you need. In my opinion, practicing setting up ahead of time is the single most important thing home chefs can do for professional results — whether thickening soups or making any other dish.