How to Thicken Potato Soup

Thickening the Soup with Starch

Add a roux to add the most thickness to your soup. A roux is made by heating up equal parts flour and fat to add body and flavor to a dish. To thicken about 1 qt (0.95 L), melt 2 tbsp (28 g) of butter in a skillet, then whisk in 2 tbsp (30 g) of flour. Continue cooking the mixture, stirring constantly, until it's a blond color, or just starting to darken. Then, stir the roux into your soup just before it's finished cooking. If you want to add a nutty flavor to your soup, cook the roux until it's about the color of peanut butter. However, a lighter roux will thicken your soup more effectively. Since you're not baking with it, you can use either self-rising or all-purpose flour to thicken your soup.

Make a slurry with cornstarch or flour for a very thin soup. Whisk 2 tbsp (25 g) of cornstarch or 2 tbsp (30 g) of flour with ⁄4 cup (59 mL) of cool water. Once the starch is completely dissolved, pour the slurry into the main pot. Heat the soup to boiling for 1 minute, then reduce the heat and simmer until the soup is as thick as you’d like it. By mixing the flour or cornstarch with cool water before adding it to the soup, you’ll keep it from clumping up when it hits the hot liquid. This will thicken about 1 qt (0.95 L) of soup. Tip: Cornstarch will thicken your soup more than flour, but both are a good option if you need to thicken a very thin soup.

Pour in 1 cup (60 g) of instant potato flakes for a quick fix. This will add extra potato flavor to your soup, so you don't have to worry about changing the taste. Add the instant potatoes to your soup at the end while it's simmering, then cover the pot and wait about 5 minutes. This will thicken about 2 qt (1.9 L) of soup, and these potato flakes will add a lot of body. Adjust the proportion as you need to.

Make a beurre manie from butter and flour to thicken the soup at the end. To thicken about 1 qt (0.95 L) of soup, take 2 tbsp (28 g) of softened butter and 2 tbsp (30 g) of flour and place them in a bowl, then knead them together with your hands. When the mixture is completely combined, it should be crumbly. Add in the crumbles a little at a time to your hot soup, right before it’s finished cooking, until it reaches the desired consistency. Beurre manie is a French technique that’s similar to making a roux. The butter coats the individual grains of flour, which is why they won't lump up when you add them to hot soup. This will add a moderate amount of thickness to your soup.

Tear up chunks of bread and soak them in broth to add moderate thickness. Tear up 3-4 slices of bread into large chunks. Then, use a ladle to spoon some of the soup into a bowl. Add in the chunks of bread and let them dissolve, then puree them in a blender or a food processor. Pour the mixture back into the soup and stir it well. You should see the effect right away. You may want to remove the crusts if you're using French bread or another bread with a flaky crust, as it may not completely dissolve. However, since you're pureeing it, you may choose to leave the crusts on if you prefer. Stale bread will thicken the soup more than fresh loaves. This should give you about 2 cups (75-100 g) of bread crumbs, which will thicken 1 qt (0.95 L) of soup.

Mixing in a Creamy Element

Pour in a little cream to add thickness and a silky texture. Adding cream to your soup will help thicken it, and it will give the potato soup a creamy, silky texture. In addition, the cream adds a rich flavor that goes perfectly with potato soup. Measure the cream into a bowl, then add a little of the hot soup to the bowl to temper it, or to bring it gently up to temperature. Then, pour the mixture back into the soup and stir well. The amount you add will depend on how much soup you made and how much you need to thicken it. Start with 1–2 US tbsp (15–30 mL), then add more if you need to. If your soup is very watery, adding another liquid will only help so much. You may want to consider adding a roux or another starch instead. Tip: Do not boil the soup after you add dairy, or it may curdle.

Add a dollop of yogurt to thicken your soup while adding a tangy flavor. Yogurt will thicken a soup in a similar way to cream, but it adds a noticeable tangy flavor to the dish, and it results in a lighter soup. Temper the yogurt by mixing it with a little of the hot soup before you pour it in, which should keep it from curdling. The taste of the yogurt especially suits potato soups containing a sharp cheese like cheddar. Since yogurt affects the taste of the soup, this approach may be best for thickening individual servings.

Stir in coconut cream for a dairy-free option. Coconut milk is thick and creamy, with a subtle coconut flavor. Try stirring about ⁄4 cup (59 mL) into 1 quart (0.95 L) of soup to add richness to the broth, while avoiding the use of dairy. This amount won't have much effect on the flavor of the soup. If you do want to taste the coconut, add about ⁄2 cup (120 mL) of the cream instead. The mild flavor of coconut pairs especially well with potato soups made with goat cheeses like chèvre and goat brie.

Trying Other Thickeners

Puree 1–2 cups (240–470 mL) of the soup to thicken it without adding anything. Use a ladle to spoon out about 1–2 cups (240–470 mL) of the soup, including a few pieces of the potatoes and anything else in the soup. Then, use an immersion blender or a food processor to puree the portion of the soup that you removed until it’s completely smooth. Pour this mixture back into the soup to thicken it instantly. Since adding starches or creamy elements can alter the flavor of the soup, this is a great option if you’re happy with the taste and don’t want to change it.

Stir in pureed nuts to add protein. Take about 1/2 cup (75 g) of nuts like almonds, cashews, or walnuts, and grind them in a food processor or spice grinder. When the nuts are completely broken down, mix them with about ⁄4 cup (59 mL) of the liquid from the soup, then add them back into the rest of the potato soup. This should thicken about 1 qt (0.95 L) of soup. If you're serving others, make sure no one has a food allergy before you add nuts to the dish! The nutty flavor will complement rich, meaty potato soups, like a recipe that includes smoked ham or bacon.

Stir in cheese and let it melt for a little extra thickness at the end. Cheese and potatoes are made to go together, so this is a delicious way to get a little additional thickness after your soup is cooked. You can either add 1 cup (125 g) of shredded cheese to the whole pot of soup (or more if needed), or you can sprinkle shredded cheese directly on top of your bowl if you prefer. Sharp cheeses like cheddar or Monterey jack work especially well in potato soups, but feel free to experiment with your favorite cheese!