This slow cooker tomato soup delivers deep, velvety flavor with minimal effort. The long, gentle simmer coaxes out the natural sweetness of tomatoes and creates a rich, comforting bowl. Set it and forget it for the easiest homemade tomato soup.
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Why You’ll Love This Slow Cooker Tomato Soup
- Hands-off cooking: Your slow cooker does all the work while you relax.
- Deep, complex flavor: Slow cooking caramelizes vegetables for a rich, sweet-savory taste.
- Wonderfully versatile: Enjoy it smooth or chunky, creamy or dairy-free.
- Amazing aroma: Fills your home with an incredibly comforting scent.
Ingredients & Tools
- 2 tbsp olive oil
- 1 large yellow onion, roughly chopped
- 4-5 cloves garlic, smashed
- 2 (28 oz / 800 g) cans whole peeled tomatoes (with their juices)
- 1 cup (240 ml) vegetable broth
- 2 tsp dried oregano
- 1 tsp dried basil
- 1 tbsp tomato paste
- 1 tsp granulated sugar (optional, to taste)
- ½ cup (120 ml) heavy cream or full-fat coconut milk (optional, for creaminess)
- To taste: salt and freshly ground black pepper
- For serving: fresh basil, a drizzle of cream, or crusty bread
Tools: A 6-quart or larger slow cooker, an immersion blender or standard countertop blender
Notes: Using good-quality canned tomatoes really makes a difference here—look for San Marzano if you can, as they have a wonderful sweet flavor and less acidity. And don’t skip the onion and garlic; they form the savory foundation that makes this soup so satisfying.
Nutrition (per serving)
| Calories: | 180 kcal |
| Protein: | 4 g |
| Fat: | 10 g |
| Carbs: | 22 g |
| Fiber: | 5 g |
Serves: 6 | Prep Time: 15 minutes | Cook Time: 6 hours (Low) or 3 hours (High) | Total Time: 6 hours 15 minutes (Low)
Before You Start: Tips & Ingredient Notes
- Why use whole peeled tomatoes? They often have a better, less metallic flavor than pre-diced tomatoes and break down beautifully during the long cook time, giving you a wonderfully smooth texture.
- Should I sauté the onions and garlic first? You can add them raw for ultimate ease, but if you have 5 extra minutes, sautéing them in the olive oil until softened will add a deeper, sweeter flavor base to your soup.
- What’s the deal with the optional sugar? A little sugar can help balance the acidity of the tomatoes, but the slow cooking process naturally sweetens them, too. Always taste at the end and add only if you feel it needs it.
- Can I make it creamy from the start? Hold off on adding any dairy or coconut milk until the very end. Adding it before the long cook can cause it to separate or curdle, giving you an unpleasant texture.
How to Make Slow Cooker Tomato Soup
Step 1: Start by prepping your vegetables. Roughly chop the onion—don’t worry about perfect dice, as everything will be blended later. Smash the garlic cloves with the side of your knife to release their flavorful oils. If you’re taking the extra step, you can now sauté these in the olive oil in a pan over medium heat for about 5-7 minutes, until the onion is translucent and fragrant.
Step 2: Transfer the onion and garlic mixture (or the raw onions and garlic if skipping the sauté) into the bowl of your slow cooker. Pour in the entire contents of the two cans of whole peeled tomatoes, including all the precious juices. The juices are packed with flavor and will help create the perfect soup consistency.
Step 3: Add the vegetable broth, dried oregano, dried basil, and tomato paste to the slow cooker. Use a wooden spoon to gently break up the whole tomatoes a little and stir everything together until the tomato paste is dissolved. You’ll notice the broth will start to take on a lovely red hue almost immediately.
Step 4: Cover with the lid and set your slow cooker. You have two great options here. For the most developed flavor, cook on LOW for 6-7 hours. If you’re short on time, you can cook on HIGH for 3-4 hours. The soup is done when the onions are completely tender and the flavors have melded together beautifully.
Step 5: Once the cooking time is up, it’s time to blend. For the smoothest texture, use an immersion blender directly in the slow cooker pot. If using a countertop blender, work in batches, filling the blender no more than halfway, and hold the lid down with a towel—the soup is very hot and can cause the lid to pop off. Blend until completely smooth and velvety.
Step 6: Now, taste your masterpiece. This is the moment to season with salt and pepper and decide if you’d like to add the optional sugar to balance the acidity. If you’re using cream or coconut milk, stir it in now until fully incorporated. The soup will turn a gorgeous, lighter orange-pink color and become luxuriously creamy.
Step 7: Let the soup heat through for another 10-15 minutes on the WARM or LOW setting after adding any final ingredients. Give it one final stir, ladle into bowls, and garnish with a swirl of cream, a few fresh basil leaves, and a generous grind of black pepper. Serve immediately and enjoy the fruits of your (very minimal) labor.
Storage & Freshness Guide
- Fridge: Cool completely and store in an airtight container for 4–5 days.
- Freezer: Portion into freezer-safe containers or bags and freeze for up to 3 months.
- Reviving: Reheat gently on the stovetop or in microwave, stirring well. Add a splash of broth if too thick.
Serving Suggestions
Complementary Dishes
- Grilled Cheese Sandwich — The classic pairing for a reason. The crispy, buttery bread and gooey, melted cheese are the perfect textural contrast to the smooth, hot soup.
- Simple Arugula Salad — A light salad with a sharp lemon vinaigrette cuts through the richness of the soup and adds a fresh, peppery bite to the meal.
- Garlic Bread or Crusty Baguette — Essential for dipping and scooping up every last bit of soup from the bottom of your bowl. You’ll want something to soak up all that goodness.
Drinks
- Crisp White Wine — A Sauvignon Blanc or Pinot Grigio with its bright acidity complements the tomatoes beautifully and cleanses the palate between spoonfuls.
- Sparkling Water with Lemon — The bubbles and citrus are wonderfully refreshing and help balance the savory, rich notes of the soup without overpowering it.
- Iced Herbal Tea — A chilled, non-caffeinated tea like peppermint or rooibos offers a cool, soothing counterpoint to the warm, comforting soup.
Something Sweet
- Lemon Sorbet — Its bright, clean, and tart flavor is the perfect palate-cleanser after a savory meal and feels light and refreshing.
- Dark Chocolate Truffles — Just one or two rich, intense truffles provide a decadent yet small finish that doesn’t leave you feeling overly full.
- Shortbread Cookies — Their simple, buttery sweetness and crumbly texture are a delightful, gentle end to a comforting lunch or dinner.
Top Mistakes to Avoid
- Mistake: Using canned tomatoes with added seasonings. Stick to plain whole peeled tomatoes. Tomatoes that are pre-seasoned with Italian herbs or basil can make your final soup taste bitter or overly salty after the long cooking time.
- Mistake: Adding dairy too early. I’ve messed this up before too—adding cream, milk, or even coconut milk at the beginning will cause it to curdle and separate. Always stir it in at the very end, just before serving.
- Mistake: Not blending until completely smooth. A few chunks of tomato or onion might seem fine, but for that truly restaurant-quality, velvety texture, you need to blend for a full minute or two until no bits remain.
- Mistake: Underseasoning at the end. Tomatoes and broths vary in salt content. The slow cooking process mellows flavors, so your soup will almost always need a generous final seasoning of salt and pepper to make the flavors pop.
Expert Tips
- Tip: Roast your garlic first. For an even deeper, sweeter, and less pungent garlic flavor, wrap a whole head of garlic in foil with a drizzle of oil and roast at 400°F (200°C) for 40 minutes. Squeeze the soft, caramelized cloves into the slow cooker.
- Tip: Add a parmesan rind. If you have one stashed in your freezer, toss a parmesan rind into the slow cooker with the other ingredients. It will melt into the soup, adding an incredible layer of umami and richness.
- Tip: Cook a double batch for meal prep. This soup freezes magnificently. Let it cool completely, then portion it into airtight containers or freezer bags. It will keep for up to 3 months, giving you a instant homemade meal on a busy day.
- Tip: Finish with a splash of acid. If the soup tastes a little flat after blending, a small squeeze of fresh lemon juice or a tiny dash of balsamic vinegar can brighten all the flavors and make them sing.
FAQs
Can I use fresh tomatoes instead of canned?
You can, but it requires a bit more work. You’ll need about 3-4 pounds of fresh, ripe Roma or plum tomatoes. The key is to blanch them first to remove the skins: score an “X” on the bottom, drop them in boiling water for 60 seconds, then into an ice bath. The skins will peel right off. Then proceed with the recipe. Honestly, canned are often more consistent and convenient, especially when good fresh tomatoes are out of season.
How long does this soup keep in the fridge?
Stored in an airtight container, your homemade tomato soup will stay fresh in the refrigerator for 4-5 days. The flavors often meld and improve after a day, making fantastic leftovers. Just reheat it gently on the stovetop or in the microwave, giving it a good stir before serving.
My soup is too thin. How can I thicken it?
If your soup is thinner than you’d like, the easiest fix is to let it simmer uncovered in the slow cooker on HIGH for 20-30 minutes to evaporate some liquid. Alternatively, you can make a quick slurry by mixing a tablespoon of cornstarch with two tablespoons of cold water and stirring it into the hot soup, letting it cook for a few minutes until thickened.
Can I make this soup vegan or dairy-free?
Absolutely! This recipe is naturally vegan until you add the cream. Simply omit the heavy cream or use a can of full-fat coconut milk for a rich, creamy, and completely plant-based version. Just be sure to check that your vegetable broth is certified vegan, as some brands can contain hidden animal products.
Is it safe to leave the slow cooker on while I’m out of the house?
Modern slow cookers are generally designed to be safe for unattended use. They operate at a low wattage and are built to cook for extended periods. However, always follow your appliance’s manual, ensure it’s on a stable, heat-resistant surface away from anything flammable, and use the specified settings (LOW is ideal for longer, unattended cooks). If you have any doubts, it’s best to cook it on a day you’re home.
Slow Cooker Tomato Soup
Make the best Slow Cooker Tomato Soup with minimal effort. This rich, comforting recipe is perfect for busy days. Get the easy recipe now!
Ingredients
For the Ingredients
-
2 tbsp olive oil
-
1 large yellow onion (roughly chopped)
-
4-5 cloves garlic (smashed)
-
2 cans whole peeled tomatoes (28 oz / 800 g each, with their juices)
-
1 cup vegetable broth (240 ml)
-
2 tsp dried oregano
-
1 tsp dried basil
-
1 tbsp tomato paste
-
1 tsp granulated sugar (optional, to taste)
-
1/2 cup heavy cream or full-fat coconut milk (optional, for creaminess, 120 ml)
-
salt and freshly ground black pepper (to taste)
-
fresh basil, a drizzle of cream, or crusty bread (for serving)
Instructions
-
Start by prepping your vegetables. Roughly chop the onion—don’t worry about perfect dice, as everything will be blended later. Smash the garlic cloves with the side of your knife to release their flavorful oils. If you’re taking the extra step, you can now sauté these in the olive oil in a pan over medium heat for about 5-7 minutes, until the onion is translucent and fragrant.01
-
Transfer the onion and garlic mixture (or the raw onions and garlic if skipping the sauté) into the bowl of your slow cooker. Pour in the entire contents of the two cans of whole peeled tomatoes, including all the precious juices. The juices are packed with flavor and will help create the perfect soup consistency.02
-
Add the vegetable broth, dried oregano, dried basil, and tomato paste to the slow cooker. Use a wooden spoon to gently break up the whole tomatoes a little and stir everything together until the tomato paste is dissolved. You’ll notice the broth will start to take on a lovely red hue almost immediately.03
-
Cover with the lid and set your slow cooker. You have two great options here. For the most developed flavor, cook on LOW for 6-7 hours. If you’re short on time, you can cook on HIGH for 3-4 hours. The soup is done when the onions are completely tender and the flavors have melded together beautifully.04
-
Once the cooking time is up, it’s time to blend. For the smoothest texture, use an immersion blender directly in the slow cooker pot. If using a countertop blender, work in batches, filling the blender no more than halfway, and hold the lid down with a towel—the soup is very hot and can cause the lid to pop off. Blend until completely smooth and velvety.05
-
Now, taste your masterpiece. This is the moment to season with salt and pepper and decide if you’d like to add the optional sugar to balance the acidity. If you’re using cream or coconut milk, stir it in now until fully incorporated. The soup will turn a gorgeous, lighter orange-pink color and become luxuriously creamy.06
-
Let the soup heat through for another 10-15 minutes on the WARM or LOW setting after adding any final ingredients. Give it one final stir, ladle into bowls, and garnish with a swirl of cream, a few fresh basil leaves, and a generous grind of black pepper. Serve immediately and enjoy the fruits of your (very minimal) labor.07
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