How to Thicken Tomato Soup: 6 Ways to Thicken Soup

Tomato soup, or tomato bisque, is a comfort food for many around the globe, particularly those in Poland and the United States. The main ingredient is a tomato product—either fresh tomatoes (ideally San Marzano tomatoes), roasted tomatoes, or canned tomatoes in combination with tomato paste. Tomato soup also consists of garlic cloves and yellow onion, which you sauté first to bring out their flavors. Additional ingredients include fresh basil leaves, salt, black pepper, red pepper flakes or cayenne pepper, and chicken broth or vegetable broth. The addition of oregano and Parmesan rinds can give the soup an Italian flavor profile, while adding peppers, red onion, and paprika will give the soup a more Spanish flavor.

Tomatoes have a high water content, and the addition of broth and cold water can lead to a thin tomato soup, especially when you’re making the dish in a slow cooker. Here are a few tips that will help you prevent a watery tomato soup:

• Drain the liquid from canned tomatoes. If a tomato soup recipe calls for canned tomatoes, drain the liquid from the can before you add the tomatoes to the pot. The liquid lacks flavor and will only make your soup watery.
• Avoid rinsing the can. After home cooks pour canned tomatoes into the pot, they sometimes rinse the can out with water to get every last bit of tomato, and then they pour the water into the pot. But doing this introduces more water into the recipe and increases the cooking time to allow the excess liquid to evaporate.
• Roast the tomatoes. Taking the time to roast tomatoes before adding them to your soup will intensify their flavor and dry them out. Use roasted tomatoes instead of or in conjunction with canned tomatoes to limit the amount of water in your dish.
• Start with a small amount of broth. If the homemade tomato soup recipe calls for a certain amount of chicken stock or vegetable stock (preferably low-sodium stock), add half that amount to start. You can always add more later on if the soup is too thick. Also, try using a homemade chicken bone broth, which will be naturally thicker from the collagen in the bones.
• Use tomato purée or tomato sauce. Instead of starting with canned diced tomatoes, crushed tomatoes, or whole tomatoes, start with tomato purée or tomato sauce. Both of these ingredients are naturally thicker than traditional canned tomatoes and will carry a stronger tomato flavor.

If you have followed a tomato soup recipe to the letter and found that the soup is thinner than you would prefer, there are steps you can take to thicken it.

1. 1. Add cream. Dairy options high in fat will create a thick and creamy consistency in dishes. Try adding heavy cream, half-and-half, sour cream, or even cashew cream to thicken a creamy tomato soup.
2. 2. Blend the soup. Purée the whole soup or just half of it to add thickness to the dish. Use a food processor or high-powered blender to purée the soup in batches, or use an immersion blender to blend the whole thing all at once right in the pot. This is one of the easiest ways to thicken a soup without changing the flavor profile.
3. 3. Incorporate vegetables. If your tomato soup is too thin, try adding cubed sweet potatoes, butternut squash, or other veggies to absorb some of the excess liquid. Alternatively, you can add quinoa or lentils, which will absorb water as they cook in the soup, thickening it naturally. Note that this will add some additional prep time to the total time of the recipe.
4. 4. Make a slurry. Some dishes begin with a roux (a thickening agent of equal parts all-purpose flour and olive oil or unsalted butter) to ensure their thickness. When you use this technique toward the end of the cooking process, it’s called a slurry. To make a slurry, mix a spoonful of cornstarch or tapioca starch with some of the excess liquid from the soup. Stir to combine the ingredients, and then add the mixture right into the soup. Bring the soup to a boil and watch it thicken almost immediately.
5. 5. Reduce the soup. To avoid changing the flavor of a creamy tomato basil soup or having to add other ingredients, you can try simmering the soup over low heat or medium heat for additional time. This allows excess liquid to cook off, which will concentrate the tomato flavor and naturally thicken the soup.
6. 6. Top the soup with croutons. Bread soaks up liquid easily, so you can try adding toasted croutons to tomato soup as it cooks to thicken the dish. The bread will break down in the soup and become almost nonexistent. Alternatively, you can garnish the soup with the croutons, which will absorb the soup more slowly.

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