10 Different Ways To Thicken Tomato Soup

I don’t know about you but I never seem to get the texture right when making tomato soup from scratch. It’s because fresh tomatoes are mostly water and can never give the same (consistent) results as the canned ones. So, I had to master the art of fixing watery tomato soup.

I have 10 tried and tested methods to share and each one will enhance your recipe in its own special way. So, let’s learn about different ways to thicken tomato soup.

Add potatoes when cooking your veggies

thicken tomato soup

Potatoes are brimming with starch that will naturally thicken any liquid. They also have this natural sweetness that will compliment tomatoes beautifully. But you have to get the right potato and prep it correctly for this method to work.

The fix: I usually cook with Roma tomatoes so I find that a single potato is enough for the job. If you’re using another breed, feel free to use at least 2 medium Yukon Golds. And Yukon Golds you must use! They have a lot of starch which allows them to make super silky mash and to thickens soups and stews beautifully.

The way you cut the is also very important. You want to first slice them into half-inch slices, then cut each slice into 8 triangles. This increases the surface-to-mass ratio and allows for more starch to seep out into the soup. This is also the cut you want to use next time you’re making mashed potatoes.

Then, add the potatoes at the very beginning. If you’re adding a stock of any kind to the soup, you can use it to give a headstart to the potatoes. Add the stock to another pan and drop the potatoes inside. Let it come to a boil on medium heat. Turn the hob off, place a lid on the pot and leave the potatoes to steam while you prep everything else. Add the stock and the potatoes to other veg and live them to simmer.

The magic of instant potato flakes

You don’t have to like instant mashed potatoes to make this a staple in your pantry. Instant potato flakes are a great thickener that you can use whenever you don’t want to overload the dish with flour or starch (be it because of flavor or you’re doing paleo or whatever). You’re basically using half the amount of starch and about a quarter of flour! Plus, you can add them directly to the pot and get instant results.

But make sure that you get the kind that only needs boiled water and no additional cooking. The other stuff will work as well, but it’s not as easy to gauge when you’ve had enough of it.

Add roux

The French method of making basic tomato sauce starts with a roux. We are basically doing the same thing but adding about twice as many tomatoes.

A roux formula is simple: 1 tablespoon of butter, 1 tablespoon of flour, and 1 cup of liquid. That means that you will use a tablespoon of each butter and flour per two cups of chopped or pureed tomatoes. Let’s give it a go.

The fix: In a heavy-bottomed pan, melt the butter over high heat. Sprinkle the flour and start whisking. Whisk continuously for at least 10-15 minutes to create a blond roux (good enough for this recipe), or take it further until it starts to look like peanut butter and smell nutty. Add the tomatoes (and other ingredients) and mix through, lower the heat, and simmer.

Add starches

Of course, this was going to be on a list of solutions. Starches are constantly used as thickeners in cooking, and tomato soup is no different. You also have a whole host of them to choose from: starting with cornstarch that is probably already in your cupboard, to tapioca starch that will give an Instagram-worthy gloss to the soup.

However, don’t just dump that stuff in and follow these few steps.

The fix: The perfect amount is 1 tablespoon of starch per pound of tomatoes. You can go for a bit less if you’re using Roma.

First, make a slurry. For each tablespoon of starch, you’ll need 2 tablespoons of water. Then, add the slurry into the blended soup and whisk vigorously. You can even add the starch during the blending, but do this only when the soup is already smooth and you’re not using a stick blender. Stick blenders work a section at a time and may not distribute the slurry throughout.

Add flour

Flour is pretty much a good alternative if you’re out of starch. But instead of 1 tablespoon, you’ll have to use 2 to make a slurry. The same ratio remains, which means that 2 tablespoons of flour should be okay for 1 pound of tomatoes.

The fix: While it’s okay to make a water slurry when using starch, it’s better to take out some of the soup for this method (make a slurry with half soup half water). Other than that, follow the same instructions from the previous section.

Add +35% cream

This is a simple switch that will help thicken tomato soup. If your recipe already calls for cream, just skip the regular cooking cream (which is about 10% fat) to 35%.

The fix: Wait for the soup to cool down to the eating temperature before adding cream. The heat and the acidity in tomatoes will make it curdle if you’re not careful.

If you can’t find 35% cream in your local grocery store, pick up some 35% sour cream. You will not be able to just stir it through as with regular cream and you’ll have to blitz it with a blender, but it will give amazing brightness to the soup.

Add more veggies

Most red and orange veggies (all of them being a great option for adding to a tomato soup) don’t have as much starch as potatoes. Still, they make for a great option if you want to give more body to your recipe.

However, keep in mind that they may hijack the flavor as well. Especially something like pumpkin or peppers will come through. If you’re going for this method to hide veggies from your kids, you’ll have to watch how much you’re adding.

Sweet potatoes and carrots are great because they don’t come out as strong. Different color veg like zucchini or eggplants will dilute the color, but you can add a bit of beetroot to fix that in a jiffy.

The fix: If you know that your tomato soup always comes out a bit watery, follow it per usual but simply add more veg to the pot when you start simmering. About 3:1 ratio will work foremost types of fresh tomatoes -3 parts tomato and 1 part other veg. You can go as much as 2:1 but keep an eye on it and do a taste test to see if you lost too much of the tomato flavor.

Simmer your soup for longer

Nothing in your cupboards that you can use to thicken tomato soup? Simply leave it on the hob to simmer for a bit longer.

Have you ever made a reduction of any kind: a pan sauce or dulce de leche? Well, it’s the same process and principle here. As the soup slowly simmers away, more water will evaporate and it will naturally thicken.

However, there are a few things to keep in mind. First, this will have a huge impact on the final flavor. Tomatoes have a lot of sugar that will continue to caramelize as the soup continues to cook. Also, some of the more volatile flavor compounds in fresh tomatoes will cook away as well.

Second, this method requires time. You can just turn up the heat in the hopes of making things go faster. If you try to do that you’ll end up with burnt soup. To quote my favorite TVcook, your patience will be


The fix: Transfer the soup into the widest cooking vessel you own. If you can use a large baking pan on your hob, that would be ideal. If not, pull out every frying and saute pan in your collection.

The key is to achieve a large surface-to-mass ratio. This will make the moisture evaporate faster, therefore not overcooking the soup and changing the flavor a lot.

Add nuts or lentils

Both nuts and lentils are great for adding more nutrients to a humble bowl of tomato soup. My favorite option is red lentils, and not only because of the color but because they melt into the soup easily. Nuts require a bit more planning, but they bring amazing richness to the soup.

Fix 1 – Lentils: Red lentils take very little time to cook so you can add them in the last stages if you want (or if you realize late that you’ll need to use them as a thickener). Green and brown lentils need to be added in the very beginning so they are not the best suitable for a quick fix. Stick to the red to make things easy.

Red lentils need 3 cups of liquid per cup of dried lentils. Depending on the type of tomatoes you’re using, this can mean that you need anything from a tablespoon to about half a cup of lentils for a 4-quart batch of soup. Start with an ounce of lentils per quart of finished soup and keep an eye on it. You may need to add more water or more lentils by the end.

If you’re adding lentils at the end, put the lid on and give the soup another 10-15 minutes. Then blend as usual.

Fix 2 – Nuts: Unless you have time to leave the whole nuts to marinate in tomatoes overnight, make some nut flour. Whole nuts take hours to absorb liquid while nut flour will do it in a fraction of time.

Add 1-2 tablespoons of nut flour for every quart of finished tomato soup. Do this at the beginning of cooking so the nuts have plenty of time to absorb excess liquid. Cashews will work the best because of their neutral flavor and absorbency, but you can use any other nut you like as long as it’s raw.

Add bread

One of the most delicious cold soups, gazpacho, uses bread as a thickener. The ingredients are chopped and mixed, then left to marinate overnight (at least according to my recipe). Then, once you’re ready to serve, everything is blitzed in a blender and the magic spell is complete.

But will this work with a hot tomato soup as well? Of course. Plus, there is another way to use bread to deal with watery tomato soup.

The fix: You can use anything from Wonder Bread to crusty artisanal loaves for this method. The only thing that matters is how dry it is. Stale bread will absorb more liquid, but you can also toast the fresh stuff to dry it out a bit.

Your first option is to add a couple of slices of bread to the soup and let it absorb some of the liquid and soften before blending everything – just like a gazpacho.

Or you can make croutons and let them both absorb excess moisture and add some texture to the soup. But make sure that they are super dry. Store-bought croutons are ideal, but if you want to make some from scratch, place them in the low oven or food dehydrator to dry them out completely. If they feel like they could knock out a tooth if you try to eat the “raw”, you did a good job.

Add cheese

What goes better with tomatoes than cheese? This method works almost the same as adding cream, but it’s way more delicious. Obviously, it will change the original flavor of the soup, but it’s a yummy change that you will not mind one bit.

Almost any kind of cheese will work, but for some, you may need to break out additional ingredients and power tools. To keep it simple, pick a melting cheese. Havarti and Fontina are my top picks since they taste very buttery and slightly sweet, but Colby, Provolone, and blue cheese are great picks as well.

The fix: If you’re using a melting cheese, simply add it to the pot at the end of cooking and stir through. As long as the soup is piping hot when you serve it, you can also leave the cheese on the side and let everyone add however much they want.

But if you want to use a cheese that doesn’t melt so well, you will have to make a cheese sauce first. I hope you have mastered your mother sauces because you will have to make a bechamel. Then you will have to blend the cheese until it’s smooth. But don’t put away your blender just yet because you will have to use it to blend it all with the soup as well. See? Additional ingredients and power tools.

Kitchen tools you’ll need

  • Small Brown Dry Lentils
  • Gluten Free Instant Roux
  • LARGE STOCK POT 20 Quart With Lid
  • Farberware Enamel on Steel Stock Pot/Stockpot with Lid

Bonus tip!

A few of these thickening methods will make the soup taste less tomato-ish. Here’s a tip on how to pack as much aroma not only into tomato soup but any tomato dish you’ll ever make.

Ready? Add the stalks into the dish as well.

Have you ever been to a tomato orchard? All those amazing aromas actually come from the stalks and not the fruit itself. So, essentially, we were all throwing away the best “herb” for our tomato dishes.

Save it, wash it, and treat it like a herb. Add the stalks to the pot (or the marinade in the case of gazpacho) and take it out only before blitzing the soup.


Some of the best kitchen staples for thickening watery tomato soup are flour, starch, and even instant potato flakes. But by using cheese, lentils, and veggies you can both get the desired consistency and bring more flavor to the party.

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