Slow Cooker Roasted Tomato & Basil Soup is a beautifully rich and comforting recipe that is wonderfully easy to prepare. This easy soup recipe makes a smooth, flavourful dish perfect for a simple lunch or cosy dinner.
Made with tomato, capsicum, vegetable stock and herbs, this recipe is ideal when you want something warm and satisfying with minimal effort. It’s perfect for cooler days or whenever you’re craving a nourishing homemade soup.
Originally published May 2, 2023. Updated March 19, 2026.
Making The Most Of A Garden Full Of Tomatoes
We are at that time of year where we have more tomatoes in the garden than we can possibly eat so I thought I would share a lovely recipe for you to try.
I love making soups in my slow cooker, so I wanted to show you a lovely way to make a tomato one. The key for me is to maximise the flavours from the vegetables, but make it easy too.
Roasting First For A Richer Tomato Soup
What I have done here is initially roasted the vegetables to give them more depth of flavour, then popped them in the slow cooker to finish cooking with the other ingredients. This provides a much richer result I think.
I have combined the tomatoes with basil as I think they work together so well, if you prefer you could leave this out or replace it with another complementary flavour.
Smooth vegetable soups like this Slow Cooker Tomato and Basil Soup really benefit from building flavour early. I explain those techniques in my guide on how to make the best slow cooker soup.
What You’ll Need For This Soup
- Tomatoes
- Red Capsicum
- Onion
- Garlic
- Olive Oil
- Balsamic Vinegar
- Salt & Pepper
- Dried Herbs (Oregano and Thyme or Basil)
- Sugar
- Tomato Paste
- Vegetable Stock (or Chicken Stock if you prefer)
- Fresh Basil
What sort of tomatoes are best? Any large tomato variety is fine, even cherry tomatoes will do but will not have the full flavour of the larger varieties. You need them to be ripe and red to be used.
Do I have to use balsamic vinegar? No, not at all, it just adds extra flavour
Preparing The Vegetables And Equipment
The method for this one is lovely and simple, a few steps and tools will make this much easier to make. You will want a large roasting dish, a slow cooker and either an immersion stick blender or a blender that can handle hot ingredients.
Firstly you want to prepare the vegetables. For my tomatoes I like to quarter them then very roughly remove the seeds, you don’t need to be too fussy and get every last one but it is easy enough to use your knife to scoop them out once quartered.
Roasting The Vegetables For Best Flavour
Then I dice the onion into chunks, leave the garlic peeled but whole and deseed the capsicum, slice and pop all of these vegetables into a large roasting dish.
Drizzle over this the olive oil and the balsamic vinegar and stir to coat then pop it in a hot preheated oven to roast for 30 minutes while you prepare the rest of the ingredients.
You want to use a large roasting dish so that they roast rather than cook in their own juices. If this does happen that is ok, you can simply pour off some of the juices before the next step.
Adding The Ingredients And Blending Until Smooth
Then it is just a matter of putting the roasted vegetables into the slow cooker and adding the remainder of the ingredients. I tend to use vegetable stock, but if you only have chicken stock on hand that is ok too. I add half the fresh basil at this stage then the remainder at the end.
Then slow cook on high or low until ready. Slow cooker soups can sometimes release extra liquid while cooking. If you’d like a thicker consistency, this guide on how to thicken slow cooker sauce shares several simple methods.
Then I add this to my blender or stick blender if using and blend until it is creamy and smooth. You can then add a little more basil and some salt if needed to taste and blend again.
Serving Suggestions And Storage Tips
If you wish this is lovely with a little cream stirred through at the end to make it even more creamy, but that is personal preference so feel free to taste as you go once blended.
Can I Freeze Or Refrigerate This Soup?
Yes you can, once cool, add to a suitable container or portions to a zip lock bag and refrigerate for up to 4 days or freeze for up to 3 months. Be sure to thaw and reheat slowly until piping hot but not boiling. Do not add cream if using until you are ready to eat.
Slow Cooker Roasted Tomato & Basil Soup Recipe
The full ingredient list and step-by-step instructions are in the recipe card below.
Slow Cooker Tomato and Basil Soup
Slow Cooker Roasted Tomato & Basil Soup is a rich, flavourful and easy soup made with tomato, capsicum, vegetable stock and herbs for a comforting homemade meal.
Ingredients
- 1.2 Kilograms Tomatoes, quartered, seeds roughly removed
- 1 Red Capsicum, deseeded, sliced roughly
- 1/2 Onion, sliced roughly
- 6 cloves Garlic, peeled, whole
- 1/4 Cup Olive Oil
- 2 Tablespoons Balsamic Vinegar
- 1 teaspoon Salt
- 1/2 teaspoon Pepper
- 1 teaspoon Oregano, dried
- 1 teaspoon Thyme or Basil, dried
- 1 Tablespoon Tomato Paste
- 1 Tablespoon White Sugar
- 2 Cups Vegetable Stock (chicken ok too)
- 20-25 leaves Fresh Basil
Optional
- 1/4 Cup Cream
Instructions
- Preheat your oven to 220C Bake
- Quarter your tomatoes and roughly remove most of the seeds from each quarter and add to a large roasting dish
- Deseed the red capsicum and slice, add to the roasting dish
- Slice the half onion into large pieces and peel the garlic and pop both in the roasting dish
- Combine the olive oil and balsamic vinegar and pour over the vegetables, stir to coat
- Place in the hot oven for 30 minutes until it begins to caramalise, if a lot of liquid forms you can pour some of this off before using for next step.
- Remove and place the vegetables into the slow cooker
- Add to this the salt and pepper, oregano, thyme or dried basil, tomato paste, sugar, vegetable stock and half of the fresh basil
- Stir well to combine.
- Place the lid on the slow cooker and cook on HIGH for 3 hours or LOW for 6 hours
- Once all of the ingredients are cooked carefully add to a blender that can have hot ingredients, or use a stick immersion blender and blend until completely smooth.
- Taste, then add to this the basil and extra little bit of salt to your taste and blend again until smooth
- If you prefer a a creamier finish and are eating straight away add the 1/4 cup of cream to the blender and blend again
- Serve warm with a lovely loaf of bread, or allow to cool and pop in the refrigerator for another day, or can be frozen for up to 3 months.
- Enjoy!
Notes
What sort of tomatoes is best?
Any large tomato variety is fine, even cherry tomatoes will do but will not have the full flavour of the larger varieties. You need them to be ripe and red to be used.
Do I have to use balsamic vinegar?
No, not at all, it just adds extra flavour
Can I freeze or refrigerate tomato soup?
Yes you can, once cool, add to a suitable container or portions to a zip lock bag and refrigerate for up to 4 days or freeze for up to 3 months. Be sure to thaw and reheat slowly until piping hot but not boiling. Do not add cream if using until you are ready to eat.
Nutrition Information:
Yield: 4 Serving Size: 1Amount Per Serving: Calories: 293Total Fat: 22gSaturated Fat: 6gUnsaturated Fat: 16gCholesterol: 17mgSodium: 946mgCarbohydrates: 23gFiber: 5gSugar: 15gProtein: 4g
This nutrition calculation for Just Slow Cooker Recipes has been automated, please use your discretion with the calculation and use your own if unsure.
More Slow Cooker Soup Recipes
This recipe was originally published on my other website called Just A Mum’s Kitchen – I hope you love it! You may also like my collection of slow cooker soup recipes, featuring twelve easy soups perfect for cooler days.
Below are a selection of soups that I think you will love, check them out and let me know which one you will make next.
- Slow Cooker Pumpkin Soup
- Slow Cooker Carrot & Ginger Soup
- Slow Cooker Cauliflower & Broccoli Soup
- Creamy Slow Cooker Chicken Noodle Soup
- Slow Cooker Minestrone Soup (Hearty Vegetable Soup)
I Hope You Love This Recipe
I hope you love this easy slow cooker roasted tomato & basil soup as much as we do. It’s such a lovely comforting soup for cooler autumn days and one I come back to again and again.
If you try it, I’d love to hear how it turned out for you in the comments below.
Also, if you enjoy this recipe, please leave a ⭐ rating in the recipe card above. Your feedback helps other readers and really supports my recipes.
Thank you so much for visiting and taking the time to try this recipe. I hope you find plenty of slow cooker inspiration here on my blog.
If you’d like to see more of my latest recipes and kitchen adventures, be sure to follow along on Pinterest.
Happy cooking!
Anna
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