This keto tomato soup tastes like summer in a bowl! It’s incredibly thick and creamy, with deep roasted tomato flavor, accented by fresh basil and Parmesan. It’s a delicious low carb way to use your summer produce.
This is hands-down the BEST keto tomato soup I have ever made. And I’ve made a lot of it in my decade plus of following a low carb diet.
It’s a recipe I developed last summer when I had an over-abundance of tomatoes. I threw it together without measuring, as I am wont to do when cooking for my family. I had a pan full of roasted tomatoes and I tossed in some other ingredients and let it simmer.
The minute I tasted the velvety rich flavor, I knew I had a winner on my hands. I had to make it several times to re-create the magic of that first batch. But once I nailed this roasted tomato soup recipe, I wrote it all down so I could share it with you.
And it goes so well with my Easy Keto Biscuits, too!
Why you will love this soup
This isn’t any old keto tomato soup. It’s a bit of a jazzed up version. Or perhaps I should say it’s a “souped up” version. It has added ingredients that punch up the tastiness and make it creamier. All while keeping it lower in carbs than the conventional kind.
For one thing, it uses roasted tomatoes rather than fresh. Cooking tomatoes in a high heat oven causes them to caramelize slightly, intensifying their natural flavor. Even tomatoes that aren’t quite ripe can benefit from roasting.
Then you add fresh summer basil and grated Parmesan, both of which complement tomatoes perfectly. I used a similar combination in my delectable Tomato Basil Chicken.
But this roasted tomato soup also has a secret ingredient: zucchini! Adding some fresh zucchini makes it thicker than most keto soup recipes, without any funny additives or special ingredients. You don’t taste the zucchini at all, but it helps the consistency and ups the nutrition too!
Ingredients you need
- Tomatoes: Try to pick tomatoes that are at the peak of freshness, with firm flesh and a deep red color. But as I said above, even under-ripe tomatoes benefit from roasting.
- Garlic: Fresh garlic is preferable over garlic powder.
- Zucchini: You won’t taste the added zucchini, I promise. But it adds body and thickness so I don’t recommend skipping it.
- Basil: Tomatoes and basil go together like peanut butter and jelly! Use fresh basil rather than dried.
- Whipping cream: Make it extra creamy by stirring in some heavy whipping cream at the end.
- Parmesan: Freshly grated Parmesan takes this soup from really great to absolutely fabulous! I don’t recommend the powdered kind that comes in a green can, as it’s simply not the same.
- Pantry staples: Chicken broth, olive oil, salt, pepper
Step by Step Directions
1. Roast the tomatoes: Spread the tomatoes in a baking dish and drizzle with oil. Sprinkle with salt and pepper, and roast for 30 minutes at 400ºF, until caramelized.
2. Simmer the vegetables: Sauté the garlic and zucchini in a little more oil, then stir in the tomatoes and chicken broth. Bring to a simmer and cook 10 minutes, until the zucchini is tender.
3. Blend the soup: Add the basil leaves and let wilt a few minutes. Then transfer the soup to a large blender or food processor and puree. You may need to work in batches to accommodate all the soup. You can also use an immersion blender, and blend right in the pot.
4. Return to the pot: Return the soup to the pot and stir in the heavy cream. Add the Parmesan cheese and stir until melted and combined. Taste the soup and adjust seasonings as desired.
Expert Tips
Freezing Roasted Tomatoes: If you find yourself drowning in summer tomatoes, roast them and freeze them for later use. I do this every year. I store them in unsealed pint jars until they are frozen solid, and then I add the lid.
Make sure to add all the liquid from the roasting pans, as well. Don’t miss out on that added flavor! That way, you can enjoy this Roasted Tomato Soup recipe all year long.
Canned Tomatoes: Yes, you can make this soup with canned tomatoes. It won’t quite be the same but it works. I recommend using a 28 ounce can of fire roasted tomatoes. Start at Step 2 of the instructions and add the canned tomatoes and all the juices in at Step 3.
Dairy-Free Option: Use coconut cream in place of the whipping cream and dairy-free parmesan or nutritional yeast in place of the Parmesan cheese.
Frequently Asked Questions
Tomatoes can be consumed on a keto diet, but you don’t want to over-do it. The carbs can add up quickly! That’s why this roasted tomato soup recipe includes some zucchini, to give a thicker consistency without diluting the flavor. It also adds nutrition and additional fiber.
Many store-bought soups are shockingly high in carbs and aren’t good for keto diets. They often contain added sugar and starches to make them thicker and more flavorful. However, this keto tomato soup is rich, thick, and has only 5.6g of net carbs per serving.
Fresh tomatoes have a high liquid content, but roasting them causes much of the liquid to evaporate. This concentrates the flavor, as well as caramelizes the natural sugars and enhances the sweetness. Roasted tomatoes are a great way to add a flavor boost to your favorite keto dinner recipes!
This delicious soup freezes very well. Store in glass jars or non-toxic plastic containers for up to 6 months. I recommend freezing them with no lid first, to allow the liquid to expand. Once frozen, add the lids to seal them.
Love keto soup recipes? Check out my cookbook!
Roasted Tomato Soup Recipe
Ingredients
- 2 lbs fresh tomatoes cored and coarsely chopped
- 3 tablespoon olive oil divided
- ¾ teaspoon kosher salt
- ½ teaspoon freshly ground pepper
- 4 cloves garlic minced
- 12 ounces zucchini, chopped (about 1 medium)
- 4 cups chicken broth low sodium
- ½ cup loosely packed fresh basil leaves
- ½ cup heavy whipping cream
- 2 ounces freshly grated Parmesan
Instructions
- Preheat the oven to 400ºF and spread the tomatoes in a single layer in a large glass or ceramic baking dish. Drizzle with 1 tablespoon of the oil and sprinkle with salt and pepper. Bake 30 minutes, until tomatoes have caramelized.
- In a large saucepan, heat the remaining 2 tablespoons of oil over medium heat. Add the garlic and sauté until fragrant, about 1 minute. Then add the zucchini and sauté 2 minutes.
- Stir in the tomatoes and any accumulated juices from the baking dish. Add the chicken broth and bring to a simmer. Reduce the heat and simmer 10 minutes, until the zucchini is tender.
- Add the basil leaves and let wilt. Then transfer to a large blender or food processor, or use an immersion blender, and blend until smooth. You may need to work in batches if using a blender.
- Return to the pot and stir in the whipping cream and Parmesan until the cheese is melted. Taste and adjust seasonings as desired.
Mae says
it was really bland
Carolyn says
I am not sure why that would be the case, if you roasted your tomatoes thoroughly. It’s a mellow flavor but very rich.
Cindy says
We also found it bland. It might be the fault of grocery store tomatoes.
Rachel says
Pretty good soup. I think the zucchini, while not adding any flavor, might have diluted some of the tomato flavor. Either that or my tomatoes might not have been as flavorful as I would’ve liked. I know adding the zucchini cuts down on the carb count so I’ll need to figure out how to increase the flavor without carbs! Will definitely make again.
Lee Ann says
Delicious Fall soup! I had a ton of tomatoes and accidentally doubled the recipe and I am soooo glad I did! It will be awesome to freeze it and have it later.
Jeni says
how much sodium is in this
Carolyn says
No idea but I am sure you can enter the ingredients into an online calculator.
Carmen Creecy says
Excellent soup! Very easy to prepare. My husband and I fought over the leftovers the next day!
Melissa H says
I just made this for lunch. Yum. It worked out as planned. I only added S&P. I garnished with extra Parmesan and a drizzle of cream, with a sprig of baby basil on top! It was perfectly yummy.
Caroline says
Absolutely delicious. Thanks Carolyn. Using courgette as a thickener is inspired. Brilliant. I topped mine off with a purée of basil leaves with olive oil and balsamic vinegar.
I wonder if I can use courgette to thicken watercress soup too…
Carolyn says
So glad you enjoyed it!
Tanna Worrell says
Have you tried canning this soup in a pressure canner? I wonder how the cheese would hold up?
Carolyn says
I have not! I don’t own a pressure canner.
Katie Dubé says
Ne pas mettre le fromage pour canner. L’ajouter seulement après ouverture du pot quand vous réchauffez
Do not put the cheese to canner. Add it only after opening the jar when you reheat