A rich, thick soup is a delight any time of year, but really hits the spot during the cooler months. Here are some tips on the thickening techniques you may run across as you search for soup recipes.
A roux (ROO) is a mixture of flour and fat -- such as cooking oil, butter, or chicken fat -- that is cooked, then used to thicken sauces, gravies, or soups. A common roux recipe calls for equal amounts of butter and flour, cooked in a saucepan over medium heat until the flour is absorbed by the melted butter. A roux may be cooked longer to develop a darker color and a nuttier flavor. For best results, stir the roux as it cooks.
Vegetable soups can get a big boost in flavor and body by pureeing a portion of the cooked vegetables and adding them back into the soup. Use a food processor for best results, and include some of the soup liquid to help the process along. Cooked rice can also be pureed in this way to add to soup.
When mixed with cool water and stired into hot soup, these two common kitchen starches act as thickeners. Because of their flavor-masking properties, flour and cornstarch are better used in meaty soups rather than delicate vegetable soups.
Pronounced BURR mahn-YAY, this paste is made by kneading together equal portions of flour and softened butter. Beurre manie can be added to hot soups, a little at a time, to thicken them. Though similar to a roux, beurre manie is not cooked. Add it a little at time to control the amount of thickening desired.
Occasionally, a soup recipe will call for beaten eggs as a thickening agent. Both whole eggs and yolks can be used. To avoid curdling the eggs, start by drizzling about 1/2 cup of the hot broth into the eggs, stirring vigorously while you pour. Then, add the egg mixture to the soup and cook until thickened.