This slow cooker red lentil soup, finished with a drizzle of peppery olive oil, chopped parsley and a shaving of parmesan, is thick, nourishing and full of flavour. It’s effortless to prepare and makes a comforting, budget-friendly meal that reheats and freezes well.
Lentils are one of my favourite pantry staples because they’re versatile, inexpensive and packed with nutrients. Red lentils in particular become rich and creamy when cooked, especially in a slow cooker, and they take on the flavours of the vegetables and herbs you pair them with. In this recipe they mingle with carrots, potatoes, celery, plenty of herbs and a splash of vinegar or lemon juice for brightness. A finishing drizzle of olive oil and fresh parsley lifts the bowl.
Why You’ll Love This Recipe
- Thick and hearty while still being nutritious.
- Made entirely in the slow cooker — perfect for make-ahead meals.
- Comforting winter flavours and satisfying texture.
- No precooking required: add everything to the slow cooker and let it do the work.
Ingredients needed
- red lentils
- carrots
- celery
- onion
- garlic
- potatoes
- fresh thyme
- Worcestershire sauce
- vegetable stock
- kale
- dried herbs: bay leaves, basil, oregano, sage
- for serving: olive oil, parmesan cheese, fresh parsley
See the recipe card below for exact quantities and serving details.
Step By Step Instructions
Step 1 & 2
- Chop the vegetables. Place the onion, celery, carrots, potatoes, garlic, lentils, dried and fresh herbs, Worcestershire sauce and bay leaves in the slow cooker. Pour in the vegetable stock.
- Cook on medium for about 3 hours, or until the lentils and vegetables are tender. Add the kale during the final 15 minutes of cooking so it wilts but keeps some texture.
Step 3 & 4
- When the soup is cooked, remove about one third of it and blend until smooth. Return the blended portion to the slow cooker and stir to thicken the broth and create a creamy texture.
- Add a splash of red or white wine vinegar or a squeeze of lemon to brighten the flavours. Taste and adjust salt and pepper as needed. Divide between bowls and finish with a drizzle of olive oil, chopped parsley and a sprinkle of parmesan.
Recipe FAQ’s
No. Add dried red lentils directly to the slow cooker; they’ll cook during the slow-cooking time.
You can, but results vary. Brown lentils hold their shape and have an earthy flavour; they cook in roughly 20–30 minutes. Green or French lentils are firmer and peppery and take longer to cook, so they won’t blend as smoothly. Red lentils are sweet, nutty and break down easily, giving this soup its creamy texture. For this recipe red or brown lentils are best.
Yes. If using canned lentils, cook the vegetables first for about 2½ hours, then add the drained canned lentils and cook another 30 minutes before blending a portion as directed.
Spinach will work but it wilts completely and disappears into the soup. Kale is heartier and provides more texture with this thick lentil base.
Variations
This base recipe is easy to adapt:
- Spicy – add chilli flakes or chopped fresh chilli during the last 30 minutes of cooking.
- Deluxe – top with crispy bacon or pancetta bits for a non-vegetarian version.
- Extra veggies – fold in roasted mushrooms, swede or sweet potato for added depth and texture.
Equipment
You only need a good slow cooker and a blender or food processor for this recipe. A heavy saucepan or Dutch oven with a lid can be used if you prefer to make it on the stovetop.
Storage
Lentil soup stores and freezes very well.
- Fridge – Cool quickly and store in an airtight container for up to 3 days.
- Freezer – Cool completely, then freeze in airtight containers or freezer bags for up to 3 months.
- Reheat – Thaw in the fridge overnight and reheat on the stovetop or in the microwave until piping hot. If reheating from frozen, place the sealed container under cold running water until partially thawed, then reheat thoroughly.
The Best Easy Slow Cooker Lentil Soup
Ingredients
- 1 large onion, diced
- 3–4 stalks celery, chopped
- 3 carrots, peeled and chopped
- 2 large potatoes, chopped into 2.5 cm cubes
- 165 g (about 1 cup) red lentils
- ½ tbsp dried oregano
- ½ tbsp dried basil
- 3 sprigs fresh thyme, leaves picked
- 1 tbsp sage
- 1 tbsp Worcestershire sauce
- 2 bay leaves
- 800 ml (about 3 1/5 cups) vegetable stock
- 1 tsp vinegar or lemon juice
- 50 g kale (two handfuls as a guide)
For serving
- 2 tbsp fresh parsley, chopped
- 1 tbsp olive oil
- 10 g parmesan cheese
Instructions
- Chop the vegetables and add everything except the kale to the slow cooker. Pour over the vegetable stock and cook on medium for about 3 hours, until the lentils and vegetables are tender. Add the kale for the last 15 minutes.
- Remove about one third of the soup and blend until smooth. Return it to the pot and stir to combine. Add vinegar or lemon juice, then taste and season.
- Serve in bowls with a drizzle of olive oil, chopped parsley and a sprinkle of parmesan.
Notes
To make on the stovetop
Heat 2 tablespoons of oil in a Dutch oven or heavy saucepan. Sauté diced onion for 2 minutes until translucent, add the vegetables, lentils and herbs, pour in the stock and simmer for about 45 minutes until the potatoes and lentils are tender.
Storage
- Fridge: up to 3 days in an airtight container.
- Freezer: up to 3 months in freezer-safe containers or bags.
- Reheat: thaw overnight in the fridge and reheat until piping hot.
Nutrition (per serving)
Calories: 118 kcal | Carbohydrates: 18 g | Protein: 6 g | Fat: 2 g | Fiber: 8 g