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Brown lentil soup with carrots, celery, tomatoes, and wilted spinach in a ceramic bowl.
CookingPassion

Crockpot Lentil Vegetable Soup

Make crockpot lentil vegetable soup with brown lentils, carrots, celery, and spinach. A simple meatless soup with clear timing and texture tips.
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Prep Time 20 minutes
Cook Time 8 hours 20 minutes
Total Time 8 hours 40 minutes
Servings: 6 servings
Course: Dinner
Cuisine: International
Ingredients Equipment Method Notes

Ingredients
  

  • 1½ cups (300 g) dry brown or green lentils, sorted and rinsed
  • 1 medium yellow onion, diced
  • 3 medium carrots, cut into ½-inch pieces
  • 3 celery stalks, cut into ½-inch pieces
  • 4 garlic cloves, minced
  • 6 cups (1.44 liters) low-sodium vegetable broth
  • 1 teaspoon ground cumin
  • 1 teaspoon dried thyme
  • 1 bay leaf
  • ½ teaspoon kosher salt, plus more to taste
  • ¼ teaspoon black pepper
  • 1 can (14.5 oz / 411 g) diced tomatoes with their juices
  • 3 packed cups (90 g) baby spinach
  • 1 tablespoon olive oil
  • 1 tablespoon fresh lemon juice, plus more to taste

Equipment

  • 6-quart slow cooker
  • Fine-mesh sieve
  • Ladle

Method
 

  1. Prepare the lentils. Sort and rinse the lentils thoroughly, then drain. Check that you are using whole brown or green lentils rather than split red lentils.
  2. Load the base. Add the lentils, onion, carrots, celery, garlic, broth, cumin, thyme, bay leaf, salt, and pepper to the insert. Stir so the lentils are distributed in the liquid.
  3. Cook until tender. Cover and cook on LOW for about 7–8 hours or HIGH for 4–5 hours. Start checking near the shorter end. A lentil should be soft all the way through when pressed or tasted, without a firm chalky center.
  4. Check the liquid. If the lentils need more time and the soup looks thick, add a small amount of hot water and continue cooking covered. Remove the bay leaf once the lentils and vegetables are tender.
  5. Add tomatoes and spinach. Stir in the tomatoes with their juices and the spinach. Cover on HIGH for about 15–20 minutes, until the tomatoes are heated through and the spinach has wilted.
  6. Finish the soup. Stir in the olive oil and lemon juice. Taste for salt and acidity. For a thicker soup, mash one ladleful against the side and stir it back in. Add hot broth if you prefer a looser texture.

Notes

20 minutes prep; about 7–8 hours on LOW or 4–5 hours on HIGH, plus 15–20 minutes to finish. Timings vary by appliance; check doneness as described in the method. The card time uses the upper end of LOW cooking plus the finishing stage.
Refrigerate leftovers in shallow containers within 2 hours, or within 1 hour above 90°F (32°C). Store at 40°F (4°C) or below for 3–4 days. Reheat on the stove or in the microwave to 165°F (74°C); do not reheat cold leftovers in the slow cooker.
Freeze for up to 3 months for best quality. Lentils freeze well, though the soup becomes thicker after thawing. Reheat with additional liquid, stirring from the bottom to prevent sticking.