Slow Cooker Creamy Tomato Lentil Soup

Updated: Aug. 8, 2025

Time Requirements

• Total Time: 4 hours 10 minutes (10 minutes prep + 4 hours slow cooker cooking)

• Prep Time: 10 minutes

• Cook Time: 4 hours (slow cooker, HIGH); 1 hour (stovetop, see alternative below)

Ingredients (Serves 6–8)

• Vegetables & Produce:

• 1 pound 12 ounces (≈510g) tomatoes, roughly chopped, divided (see Tomato Selection & Substitutions)

• 1 cup (150g) fresh basil: 1 large sprig (for simmering) + 1 cup roughly chopped (for finishing)

• 4 garlic cloves, smashed and finely chopped

• Legumes:

• 1½ cups (340g) red lentils, rinsed thoroughly under cold water

• Aromatics & Condiments:

• ¼ cup (32g) tomato paste

• 2 tablespoons (30ml) extra virgin olive oil

• 1 tablespoon (17g) kosher salt (e.g., Diamond Crystal)

• 1½ teaspoons granulated sugar

• 1 teaspoon dried oregano

• Freshly ground black pepper (to taste)

• Juice of 1 medium lemon (≈2 tablespoons)

• Dairy:

• ¾ cup (177ml) heavy cream (or coconut milk for a vegan twist)

Preparation Steps

Step 1: Assemble in Slow Cooker

In a 6–8-quart slow cooker, combine:

• 5 cups (1200ml) water

• 1 pound (≈450g) roughly chopped tomatoes (and their natural juices)

• Rinsed red lentils

• Smashed garlic, whole basil sprig, tomato paste, olive oil, salt, sugar, dried oregano, and black pepper.

Stir gently to distribute ingredients evenly.

Step 2: Slow Cook

Cook on HIGH heat for 4 hours (or LOW heat for 8 hours). The lentils should be tender, and the soup should coat the back of a spoon.

Step 3: Finish & Season

1. Remove the slow cooker lid and discard the basil sprig (it may break apart; no need to strain).

2. Puree lightly: Use an immersion blender to blend the soup partially (retaining some texture for a rustic feel) or transfer to a blender in batches. Return to the slow cooker.

3. Add remaining ingredients: Stir in the chopped tomatoes, fresh basil, lemon juice, and heavy cream.

4. Adjust consistency: Taste and season with salt, pepper, or lemon juice. The soup thickens as it cools; add 1–2 tablespoons of water if too thick.

Stovetop Alternative (≈1 hour)

Combine all ingredients except the heavy cream, remaining tomatoes, and fresh basil in a large pot. Bring to a boil, then reduce heat to medium-low, cover, and simmer for 45–50 minutes (stir occasionally to prevent sticking). Proceed with Step 3 (add cream, remaining tomatoes, and basil).

Tomato Selection & Substitutions

• In-Season: Use a mix of heirloom, beefsteak, cherry, or plum tomatoes. For cherry tomatoes, choose thin-skinned varieties (e.g., Sungold) to minimize skin texture.

• Out-of-Season: Start with a 15-ounce (425g) can of crushed tomatoes, then finish with ½ cup chopped fresh cherry/grape tomatoes (less seedy).

• Roasted Twist: Toss whole tomatoes with olive oil and roast at 400°F (200°C) for 20 minutes for deeper sweetness before adding.

Private Notes/Tips

• Dairy Stability: Add ¼ teaspoon baking soda (not baking powder) before cream to neutralize tomato acid, preventing separation.

• Vegan Swap: Replace heavy cream with coconut milk (add 1 tablespoon cornstarch to thicken if needed).

• Spice Variations: Use Thai basil for herbal depth, or add smoked paprika for warmth.

Reader Comments

• Made with Thai basil + coconut milk: "Really good! The Thai basil adds an aromatic kick, and coconut milk gives a velvety texture."

• Stovetop Tip: "Ready in ~1 hour! Keep heat low, stir occasionally, and cover tightly."

• Dairy Hack: "Add ¼ tsp baking soda before cream—prevents grainy texture!"

This soup balances tomato brightness with creamy, herbaceous notes, perfect for cold nights or meal prep. Adjust substitutions to match what’s on hand!