Packed full of lentils and veggies, this slow cooker lentil soup is a hearty, healthy, and heart-warming meal that is perfect for a cold fall or winter day. Use this recipe for a busy weeknight dinner or a simple weekend meal prep idea to enjoy healthy lunches all week long.

On a cold day, there is nothing quite like a bowl of soup. Whether you’re warming up from a walk in the rain, ski in the snow, or just cuddling under a blanket to keep warm, a bowl of soup is sure to warm the body and the soul. Better yet, a bowl of soup that cooks itself might actually be the best kind of soup there is! Aside from a bit of chopping, this crockpot lentil soup does most of the work for you, so you can go enjoy yourself, and return to the kitchen for a hearty bowl of lentil soup that is sure to fill you up and warm you up at the same time.

What You’ll Need

This simple vegetarian soup is jam-packed with pantry and kitchen staples, here’s what you’ll need:

Lentils: You can use green lentils or brown lentils in this soup. I do not recommend using red lentils as they are very delicate and will not hold up well with the long cooking time in the crockpot.
Onions, Carrots, and Celery: This classic vegetable trio is the foundation of any good soup.
Garlic: Some freshly chopped garlic to add some flavor and fragrance.
Diced Tomatoes: A simple can of tomatoes helps to thicken the soup and add a bit of sweetness and acidity at the same time.
Kale: A generous handful of this cruciferous vegetable to add some greens. If you’re not a fan of kale, feel free to use spinach.
Vegetable Broth: I used vegetable broth in this soup to make the recipe vegetarian, however, you could certainly use chicken broth if you prefer.
Dried Herbs: A sprinkle of thyme, oregano, basil, and red chili flakes gives the soup a bit of Italian-inspired pizazz.
Red Wine Vinegar: A little splash at the end to brighten the soup and balance the flavors.
Parmesan Cheese: Finish the soup with a bit of freshly grated parmesan cheese for an extra creamy and salty bite.

Pro Tip: If you’re using fresh parmesan cheese (which I hope you are!), cut off the rind and add it to the slow cooker while the soup cooks. The rind will get super soft and break down as the soup cooks to thicken the broth and infuse the soup with a rich flavor. Simply remove whatever is left of the rind just before serving. You can also store leftover parmesan rinds in a plastic bag or container in the fridge or freezer until you are ready to use them.

Red’s Nutrition Tip

Lentils are very high in fiber and a good source of plant-based protein making them a great addition to any vegetarian meal. One cup of cooked lentils provides nearly 18 grams and 15 grams of fiber, which is more than half of the recommended daily fiber intake for an adult female and nearly half of the recommended daily fiber intake for adult males (1).

How to Make Slow Cooker Lentil Soup

This crockpot lentil soup is so easy to make it hardly needs instructions! In fact, the slow cooker does most of the work so, once you’ve got things going, you can get on with your day and return to a delicious and nutritious home-cooked meal. Here’s how you’ll make it:

Add all the ingredients, except for kale and red wine vinegar, to a slow cooker.
Stir the ingredients to ensure that everything is well combined.
Turn on the slow cooker and cook on high for 3-4 hours or low for 6-8 hours.
Once cooked, stir in the kale, and vinegar, and cook for a final 10 minutes.
Serve with desired toppings and enjoy!

Lentil Cooking Notes:

The lentils should be rinsed under cold water before cooking to remove any dust or debris.

The lentils do not need to be cooked before adding them to the slow cooker, they must be added raw.

You do not need to soak the lentils before adding them to the soup, however, they can be soaked to reduce the cooking time by up to half.

Dietary Adaptations

Make it Gluten-Free: No adaptations are needed; this recipe is naturally gluten-free.

Make it Dairy-Free: Simply make the recipe as outlined and skip the addition of parmesan cheese when serving.

Recipe Variations

This simple crock pot lentil soup is so easy to make and versatile that you can mix things up to create several variations. Here are some ideas:

Add ham, sausage, or bacon. Add 1 cup of diced cooked ham, 6 slices of sliced cooked bacon, or 2 sliced cooked sausages to the slow cooker along with the vegetables and cook as directed. Increase the broth content slightly for the ham and sausage, just enough to ensure everything is covered in the crockpot.

Add chicken or turkey. If you’d like to add more lean protein to the soup, add one pound of raw, skinless, and boneless chicken breast or thighs to the pot, along with an additional cup of broth, and cook as directed. Once cooked, remove the chicken from the slow cooker, place it on a cutting board, shred it into pieces and then return it to the soup along with the kale and vinegar.

Add more veggies. Not only can you use different vegetables in the recipe, but you can add more to boost the fiber content if you like; bell pepper, zucchini, and sweet potatoes would all work very well. Simply cut them into bite-size pieces and add them to the slow cooker along with the other vegetables and increase the broth content accordingly.

Make it on the stovetop. If you don’t have a slow cooker, you can easily make this lentil soup in a pot on the stovetop. Simply warm 1-2 tablespoons of olive oil in a pot, add the onion, carrots, celery, and garlic and sauté until tender, then add the lentils, diced tomatoes, dried herbs, salt, and broth, and bring to a boil. Then reduce the heat to medium-low, cover, and cook, stirring occasionally, until the lentils are tender, roughly 15 to 20 minutes. Once the lentils are tender, add the kale and vinegar, and cook for a final 5 minutes.

Make it in an Instant Pot. If you’d prefer to speed things up, you can easily make this lentil soup in a pressure cooker or Instant pot. Warm 1-2 tablespoons of olive oil in an Instant Pot, add the onion, carrots, celery, and garlic, and sauté until tender, then add the remaining ingredients (except the kale and vinegar as per the direction). Cover and seal the Instant Pot, and then set it to cook on high pressure for 15 minutes. Once complete, allow the cooker to release pressure naturally, and then add the kale and vinegar, stirring until the kale is tender and wilted.

Storage + Reheating

To Store: Allow the soup to cool completely and then store it in an airtight container in the fridge for up to 5 days.

To Freeze: Once the soup has cooled, transfer it to one large or individual portioned, freezer-safe, airtight containers in the freezer for up to 6 months.

To Reheat: To reheat from the fridge, transfer the soup to a pot on the stove on medium heat and cook for 5 minutes or until warm. To reheat from the freezer, remove the container from the freezer, allow the soup to thaw completely, and then transfer it to a pot on the stovetop on medium heat and cook for 5 minutes or until warm. The soup can also be reheated in the microwave in a microwave-safe dish for 1-2 minutes.

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