Richly flavorful vegetarian crockpot lentil soup is an easy and healthy family dinner. I love this soup year-round!

White bowl filled with crockpot lentil soup garnished with thyme

No matter what the season, a really good crockpot lentil soup recipe is so good to have. This soup is healthy, easy and flavorful. Combine all the ingredients in the crockpot early in the day, and dinner cooks itself.

I love having soup in the crockpot, especially the comforting, savory aroma that fills the house as it cooks. Whether you're coming home from work, working from home, or working hard all day watching kids, isn't it nice to know dinner is taken care of?

If you're looking for more lentil soup recipes, try the best lentil soup made on the stovetop or Instant Pot lentil soup with sausage.

Lentil lovers should also try slow cooker lentil Sloppy Joes and lentil bolognese.

Healthy Lentil Soup Ingredients

Brown or green lentils
Onion, garlic, celery, carrot
Curry powder, coriander, thyme
Canned diced tomatoes
Water and vegetables broth
Apple cider vinegar (just a drizzle!)

Just two spices are added to the soup - curry powder and coriander - to give the soup a subtle layer of flavor. The drizzle of vinegar before serving the soup is essential. It really boosts the overall flavor.

Before serving, you can also add baby spinach or kale, and/or coconut milk for a richer, creamier lentil soup. Fresh herbs, like parsley or cilantro, are also delicious.

Craving lentil soup with meat? Try this Instant Pot Sausage and Lentil Soup.

Do I Have to Cook Onion and Garlic Before Putting it in a Slow Cooker?

Many slow cooker recipes, like this one, include onions and garlic. Many recipes also instruct you to saute the onion and garlic (and sometimes other veggies) before adding them to a slow cooker. Is this extra step really necessary?

In my experience, the answer is yes.

It takes a long time to fully cook onion and garlic in a slow cooker. If onion and garlic aren't fully cooked the texture won't soften. Also, the flavor will be sharp instead of rich and mellow. It's not that your recipe will be ruined by undercooked onion and garlic; it just won't taste as good.

Gently cooking onion, garlic (and sometimes carrots and celery) before adding the veggies to a slow cooker can improve the overall flavor of a recipe. Sauteing onion and garlic encourages the flavor to "bloom" and browning bringing out a sweet, caramelized flavor.

But sometimes, sautéing veggies feels like too much work, doesn't it? You just want to throw everything in the slow cooker, right?

Short-Cut Trick: Microwaving onion and garlic (and other veggies) before adding them to a slow cooker is a quick short-cut trick. The veggies don't brown, but they do soften and the flavor is no longer raw.

In a microwave safe bowl, combine onion, garlic and enough olive oil to lightly coat. I usually throw in carrot and celery too, if the recipes calls for them. Microwave 6 minutes, stirring once or twice, until the onion is soft and other veggies are just tender. Lightly season with a pinch of salt and pepper. Then, add the veggies to the slow cooker.

microwaved chopped onion, ,garlic, celery and carrot

How to Make Vegetarian Crockpot Lentil Soup

Combine vegetables, seasonings, tomatoes, lentils, water and broth in the crockpot.
Put on the lid and program the slow cooker to cook for 6 to 8 hours on low heat (or 3 to 4 hours on high). The soup is done when the lentils are tender but not mushy.
Stir in a drizzle of vinegar, add salt and pepper to taste

Crockpot insert filled with uncooked lentil soup ingredients

How to Store, Freeze and Reheat Lentil Soup

Refrigerate: Leftover soup is the best! Crockpot lentil soup can be kept in the refrigerator for up to 5 days.

Freeze: Freeze lentil soup in a sealed plastic bag or freezer-safe container for up to 3 months. I like freezing individual portions in small freezer bags that I can reheat for lunch.

Reheat: Lentil soup can be reheated on the stovetop or in the microwave. Frozen lentil soup can be defrosted overnight in the fridge. Or, defrost quickly by running cold water over the freezer bag until the frozen soup breaks up and can be dumped into a pot. The soup thickens when refrigerated or frozen, so you'll need to add more water when the soup is reheated, along with more salt.

Types of Lentils

Brown and Green lentils are interchangeable and the most common and easiest to find in grocery stores. They are often used in soups, but can also be used in salads.

French or “Puy” lentils are a more expensive variety of green lentils. The texture is slightly firmer than regular green lentils.

Red and yellow lentils break down quickly and become soft and creamy. For this reason, they’re usually used to make red lentil soup or in Indian dishes like daal. Learn how to make red lentils for a variety of dishes.

Black or “beluga/caviar” lentils are a shiny black color and hold their shape very well. Learn how to cook black lentils, using either an Instant Pot or stovetop. They have a texture that is more firm than brown and green lentils. For this reason black lentils are often used in lentil salads, although they can be used in soup too.

More Soup Recipes You'll Love

📖 Recipe

Crockpot Lentil Soup

Print Recipe

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5 from 1 review

Richly flavorful vegetarian crockpot lentil soup! So easy and delicious and a healthy family dinner. I love leftovers of crockpot lentil soup for lunch throughout the week.

Author: Jenny Meier | Kitchen Skip blog
Prep Time: 15 minutes
Cook Time: 8 hours
Total Time: 8 hours 15 minutes
Yield: 6 to 8 servings
Category: soup
Method: slow cooker
Cuisine: American
Diet: Vegetarian

Ingredients

Units Scale

¼ cup olive oil
1 onion, finely chopped
4 garlic cloves, chopped or thinly sliced
2 carrots, peeled and cut into ¼ to ½ inch cubes or sliced rounds
2 celery ribs, chopped
1 ½ teaspoon curry powder
½ teaspoon coriander
1 teaspoon dried thyme a few sprigs fresh thyme
2 cups brown or green lentils
1 14-ounce can diced tomatoes
2 cups water
4 cups/32 FL oz vegetable broth
1 teaspoon salt
¼ teaspoon black pepper
1 tablespoon apple cider vinegar or red wine vinegar

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Instructions

Some slow cooker recipes require sauteing the onion and garlic before adding them to the crock pot. This is because slow cookers don't always fully cook onion, and sauteing also helps boost the flavor of onion and garlic. You can do this if you like, but I find that simply microwaving the onion and garlic (and some vegetables) achieves nearly the same results and is quicker and easier.

In a microwave safe bowl, combine olive oil, onion, garlic, carrot and celery. Microwave 6 minutes, stirring occasionally, until onion is soft and carrots are tender. Lightly season with a pinch of salt and pepper.
In the crockpot, combine the microwaved vegetables and the curry powder, coriander, thyme, lentils, tomatoes, water, broth, salt and pepper.
Put on the lid and program the slow cooker to cook for 6 to 8 hours on low heat. Or 3 to 4 hours on high.
When the soup is done, stir in the vinegar. Don't skip this ingredient! It helps boost the flavor of the soup.
Add salt and pepper to taste

Notes

Optional Ingredients/Variations: When the soup is fully cooked, you can add a few handfuls of baby spinach or kale (raw or frozen) and/or stir in coconut milk.

This recipe was made in a 6-quart oval slow cooker