Slow Cooker Lentil Soup
Brown lentils, carrots, celery and tomatoes cooked on low for 6 hours into a thick, spiced soup. Six servings, with 10 minutes of work.
Don't Make These Mistakes
Rinse the lentils and check for grit.
Add the salt and lemon at the end.
Thin with hot water; the soup thickens as it stands.
Fry the vegetables first if you have time.
Cooking Slow Cooker Lentil Soup
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Put the lentils, onion, carrots, celery, garlic, cumin, paprika, tomatoes, stock and bay leaves in the slow cooker and stir.
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Cover and cook on low for 6 hours, until the lentils are tender. If your slow cooker runs hot, check at 5 hours.
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Remove the bay leaves. Stir in the salt and lemon juice and taste.
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Thin with hot water if the soup is too thick.
Why the Method Works
It might be the easiest soup there is: chop, tip, cover, walk away. Lentils need no soaking, and over six hours they soften and release enough starch to thicken the soup without any blending.
Use brown or green lentils. Red ones dissolve entirely, which suits some soups but turns this one to a purée. Rinse the lentils in a sieve and pick out any small stones before they go in.
The vegetables go in raw, and that is fine here. If you have 5 minutes, soften the onion, carrots and celery in a little oil first, which adds a sweet note, but it is not required.
Hold the lemon and the salt until the end. Acid slows the softening of lentils, and salt can toughen their skins in some pots. Stir both in at the end and taste. The soup thickens a great deal as it stands. Loosen with hot water when serving or reheating.
Leftovers, Reheating and Keeping
Keeps in the fridge for up to 4 days. Freezes for up to 3 months. Loosen with water when reheating.
Swaps and Variations
- An eighth of a teaspoon of garlic powder per clove is the usual stand-in when you are out of fresh garlic — it will not caramelise the same way, but it carries the flavour.
What to Serve Alongside
- Crusty bread
- Yogurt
- Flatbread
- Green salad
Questions and Answers
How long does Slow Cooker Lentil Soup take to make?
About 6 hours 10 minutes in total — 10 minutes of preparation and 6 hours of cooking. The recipe serves 6.
What are the key tips for making Slow Cooker Lentil Soup?
Rinse the lentils and check for grit. Add the salt and lemon at the end. Thin with hot water; the soup thickens as it stands. Fry the vegetables first if you have time.
What should I serve with Slow Cooker Lentil Soup?
Crusty bread; Yogurt; Flatbread; Green salad.
Can Slow Cooker Lentil Soup be made ahead or frozen?
Keeps in the fridge for up to 4 days. Freezes for up to 3 months. Loosen with water when reheating.
Is Slow Cooker Lentil Soup suitable for a special diet?
This recipe is vegetarian, vegan, dairy-free and no added sugar. Those labels are checked against the ingredient list, so a dish is only marked when nothing in it contradicts the claim.
How many calories are in Slow Cooker Lentil Soup?
About 237 kcal per serving, with 16 g protein, 41 g carbohydrate and 1 g fat. The figures are calculated from the ingredient list and are an estimate.
What's in a Serving
Per serving, calculated from the ingredient list. Treat these as an estimate — brands and cuts vary.
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Written and tested by Turab
One person, one kitchen — no test kitchen, no team. How every recipe on this site is checked before it goes up.