Which lentils to use
Lentils are inexpensive, shelf-stable and do not need soaking, which makes them a good fit for the slow cooker. For more plant-based cooking, see vegan meal prep.
- Brown or green lentils: the usual choice for slow cooker soup. They soften but mostly keep their shape over several hours.
- French (Puy) lentils: firmer and slightly peppery. They hold their shape best and are a good option if you do not want a soft soup.
- Red or yellow lentils: these break down into a thick, creamy texture. They cook much faster, so they can turn to mush in a full day on low. Add them later or choose a shorter cook time.
Rinse lentils and pick out any small stones before cooking.
Simple carrot and lentil soup
Serves about 6. Prep 15 minutes. Cook 6 to 8 hours on low or 3 to 4 hours on high, depending on the lentils and your cooker.
Ingredients:
- 1 1/2 cups dry brown or green lentils, rinsed
- 1 onion, diced
- 3 carrots, peeled and diced
- 2 celery stalks, diced
- 3 cloves garlic, minced
- 1 can (14 to 15 ounces) diced tomatoes
- 6 cups vegetable or chicken broth
- 1 teaspoon cumin
- 1 teaspoon dried thyme or oregano
- 1 bay leaf
- Salt and pepper
- 1 tablespoon lemon juice or red wine vinegar, to finish
- A few handfuls of spinach or kale, optional
Steps:
- Add the lentils, vegetables, tomatoes, broth, spices and bay leaf to the slow cooker.
- Cover and cook until the lentils are tender.
- Remove the bay leaf. Stir in the greens and let them wilt for about 10 minutes.
- Add the lemon juice, then taste and season with salt and pepper.
For a creamier soup, blend about a third of it with an immersion blender and stir it back in.
Variations and a vegan option
The recipe above is vegan if you use vegetable broth. Other ideas:
- Creamy tomato lentil: add a spoonful of tomato paste and stir in a splash of coconut milk or cream at the end.
- Sausage and greens: brown sliced sausage and add it with the greens for a heartier, non-vegan meal.
- Curry style: add curry powder or garam masala and finish with coconut milk.
- Lentil stew: use less broth (about 4 cups) and add diced potatoes or sweet potatoes for a thicker, stew-like texture.
Common mistakes
- Using very old lentils: lentils stored for a long time can take longer to soften. Buy from a store with good turnover when possible.
- Adding acid too early: tomatoes and vinegar can slow lentil softening for some cooks. If your lentils stay firm, try adding the acid later and cooking a bit longer. This is a common cook’s tip rather than a hard rule.
- Salting only at the end, or not at all: lentils taste flat without enough seasoning. Taste before serving and adjust.
- Overcooking: very long cooking on high can turn lentils to mush. Check them toward the end of the cooking window.
- Skipping the finish: lemon juice, fresh herbs or a drizzle of olive oil brighten the soup noticeably.
Is lentil soup okay for people with diabetes?
Lentils provide fiber and protein, and many people with diabetes include legumes in their meals. They still contain carbohydrates, and portion size and the other ingredients in the soup matter. Because needs differ, check with your doctor or a registered dietitian about how this fits your plan.
Storage and meal prep
Cool leftovers and refrigerate them within about two hours. They generally keep three to four days in a sealed container. Lentil soup freezes well in portions; leave a little room for expansion and add greens or lemon juice after reheating. It tends to thicken as it sits, so add a splash of water or broth when warming it.
This soup pairs well with crusty bread or a simple salad. If you want more soups that go in the pot and stay there, browse our easy crockpot soups, or try the creamier crockpot potato soup.
FAQ
Do I need to soak lentils? No. Rinse them and add them directly.
Can I use canned lentils? Yes, but add them near the end, since they are already cooked and will break down with long cooking.
Why is my soup still crunchy? The lentils may be old, the cook time may be short, or the slow cooker may run low. Cook longer and check again.