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Soup recipe

Slimming World Sweet Potato and Lentil Soup

By Jenny Updated

Soup Prep: 10 mins Cook: 30 mins Serves 4
Sweet potato and red lentil soup is one of the most satisfying naturally thick soups you can make, and on Slimming World it costs absolutely nothing in syns. The red lentils dissolve into the soup as it simmers, creating a velvety, protein-rich base without any cream or butter. Sweet potato adds natural sweetness and that beautiful golden-orange colour. Cumin and ground coriander are the spices that make this soup genuinely special rather than just vegetable-flavoured water — they work with the sweetness of the potato and the earthiness of the lentil in a way that feels almost like a light dal. A squeeze of lemon at the end brightens everything.

Ingredients

Serves 4

  • 500g, peeled and diced sweet potatoes
  • 150g, rinsed red lentils
  • 1 large, diced onion
  • 3, crushed garlic cloves
  • 1.2 litres vegetable stock
  • 2 tsp ground cumin
  • 1 tsp ground coriander
  • 0.5 tsp turmeric
  • 1, juice only lemon
  • to taste salt and black pepper
  • 6 sprays Frylight cooking spray

Method

  1. 1

    Spray a large saucepan with Frylight and heat over a medium flame. Add the onion and cook for 5–6 minutes until softened.

  2. 2

    Add the crushed garlic and stir for 1 minute.

  3. 3

    Add the ground cumin, coriander, and turmeric. Stir for 1 minute to toast the spices — you will smell them bloom in the pan.

  4. 4

    Add the diced sweet potato and rinsed red lentils, stirring to coat everything in the spiced onion mixture.

  5. 5

    Pour in the vegetable stock, stir well, and bring to the boil.

  6. 6

    Reduce the heat to a steady simmer and cook uncovered for 20–25 minutes, stirring occasionally, until the sweet potato is completely tender and the lentils have dissolved into the soup.

  7. 7

    Remove from heat and use a hand blender to blitz the soup until completely smooth and velvety. Alternatively, transfer in batches to a standing blender.

  8. 8

    Stir in the lemon juice, taste, and adjust seasoning generously. Serve hot with a sprinkle of fresh coriander if desired.

Tips & swaps

Red lentils do not need soaking before cooking and dissolve naturally during simmering — this is what gives the soup its thick, creamy consistency without any blending at all if you prefer a rustic texture. A pinch of dried chilli flakes added with the spices gives a gentle warmth. For a more substantial meal, serve with a slice of HExB bread for dipping.

FAQs

Are sweet potatoes and lentils free on Slimming World?

Yes — both sweet potatoes and red lentils are free foods on Slimming World. Sweet potatoes are free but not a Speed Food, while red lentils are also free and provide excellent protein and fibre. The entire soup as written — sweet potato, lentils, onion, garlic, spices, stock, and lemon — is completely syn-free. This makes it one of the most filling, nutrition-dense free meals on the plan, with protein from the lentils and complex carbohydrates from the sweet potato.

Can I make this soup without a blender?

Yes — if you cook the soup long enough, the red lentils will dissolve almost completely into the broth and the sweet potato will become very soft. For a naturally thick but rustic texture, simply mash the soup roughly with a potato masher in the pan once the sweet potato is fully tender. The result will be chunkier than a blended version but still thick and satisfying. For a fully smooth soup, a hand blender is the most practical tool — it takes about 60 seconds directly in the pan.

Is sweet potato soup good for Slimming World weight loss?

Sweet potato and lentil soup is an excellent choice for weight loss on Slimming World. It is high in protein from the lentils, which helps with satiety. It is also high in fibre, which slows digestion and keeps you full for longer. The spices — particularly cumin and coriander — have no syn cost and add significant flavour without calories. Having a bowl of this as a starter before a main meal, or as a standalone lunch, is one of the most effective strategies on the plan for reducing overall food intake without feeling deprived.

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