A thick, hearty soup can be just like a hug in a bowl. From French onion soup, to clam chowder, a good soup should comfort and nourish you from the very first spoonful. Here are our top tips for thickening homemade soups, so you’ll get that perfect, comforting spoonful every time.
A mixture of equal parts fat and flour, roux is a common ingredient in classical French cooking, where it is used as a base for three of the five ‘mother’ sauces, including everyone’s favourite, Béchamel. But roux is also great for thickening soups, as its mild, nutty taste complements most other flavours. It also acts as a stabilising agent, so if your soup contains dairy products like cream or cheese, adding roux can help prevent curdling or splitting.
To make a roux, first measure out equal parts of fat and flour. Most people use butter for the fat, but you can also use various other types of fat, including oils and bacon grease. Heat the oil over a medium heat until a pinch of flour sprinkled into the pan just begins to bubble. Whisk in the flour, stirring continuously so the mixture doesn’t boil too vigorously.
Roux gets darker and intensifies in flavour the longer you leave it, but it also gets thinner at the same time. The best roux for thickening soup is a ‘blond’ roux, which needs about 20 minutes of whisking and stirring, until it is a light tan colour.
Allow the roux to cool before adding it to your soup. If it’s too hot it may break apart and make your soup lumpy. Add a little to your soup, whisk well and allow to simmer for around 20 minutes. At this point, the roux should have done its work, and you can tell if you need to add a little more. If you find your soup is now too thick, you can always add some liquid - stock, for example - to loosen it up.
Cornstarch is a very effective thickener, so it’s usually best to add less than you think you need. Too much cornstarch can make your soup bland, and you can always add more if it’s still too thin.
To add cornstarch to your soup, first mix it with a small amount of cold liquid, such as water, stock or wine, then stir it into the soup, a small amount at a time. Always remember to bring the soup to a simmer each time you add more of the cornstarch liquid, otherwise it won’t have any effect.
Potatoes, Rice, and Bread
You can also use starchy foods like potato, rice, and even bread to thicken your soup. Simply simmer in the soup for a long time until they break down and become a part of the liquid. You can even use a stick blender to speed up the process.
Using bread to thicken soup is popular in Mediterranean cooking, and can turn a simple soup into a hearty and filling meal. The best bread to use is something plain like a country loaf or sourdough. Avoid anything with a very dense structure, as this will be difficult to break down.
Cream, crème frâiche and sour cream add a luxuriously rich flavour and silky texture to soups, but you need to wait until the soup has cooled a little first, or they will curdle. Remove the soup from the heat and wait for a minute or two after it stops boiling, then stir in the creamy thickener of your choice. You can even wait until the soup is dished up and add a swirl of cream to each individual bowl.
Like roux, beurre manié is made from equal parts flour and butter, and it will thicken and stabilise your soup in a similar way. Here, however, there is no cooking required. All you need to do is knead the flour and butter against a clean surface until it forms a paste, then add a little at a time, always remembering to simmer afterwards, until your soup reaches the desired consistency.