Lentil and Sweet Potato Soup: A Simple One-Pot Recipe

This lentil and sweet potato soup combines red lentils, diced sweet potato, onion and cumin in one pot. Red lentils soften into the broth, so you can make a thick, comforting soup without cream or a countertop blender.

When I’m planning a straightforward dinner, this is the kind of ingredient list I look for: a few vegetables, a pantry staple and seasoning that is easy to adjust. Read the lentil notes before swapping varieties, because they affect both timing and texture.

Ingredients · Cooking method · Storage

Recipe at a glance

Serves: 4 modest bowls. Preparation: about 10 minutes. Cooking: about 30 minutes. Allow roughly 40 minutes overall; older lentils and larger vegetable pieces may take longer.

Use a large saucepan with a lid, a chopping board and a spoon. A potato masher is optional.

Ingredients

• 1 tablespoon olive oil
• 1 medium onion, finely chopped
• 2 garlic cloves, finely chopped
• 1 teaspoon ground cumin
• ½ teaspoon ground turmeric
• 2 tablespoons tomato paste
• 1 medium sweet potato, about 300 g, peeled and cut into ½-inch cubes
• 1 cup dried split red lentils, picked over and rinsed
• 4 cups vegetable broth, plus extra water as needed
• Black pepper and salt, to taste
• 1–2 teaspoons lemon juice, optional, added at the end

Choose vegetable broth for a vegan version. If you need the soup to be gluten-free, check the broth, spices and other packaged ingredients rather than relying on the recipe name.

How to make lentil and sweet potato soup

1. Warm the oil over medium heat. Add the onion and cook for about 5 minutes, stirring, until softened rather than deeply browned.
2. Add the garlic, cumin and turmeric. Stir for around 30 seconds, then mix in the tomato paste. Lower the heat if the paste starts sticking.
3. Add the sweet potato, rinsed red lentils and broth. Stir well, including the bottom of the pot, and bring to a gentle boil.
4. Reduce to a steady simmer and partly cover. Cook for about 20–25 minutes, stirring occasionally. Add a splash of water if it becomes thick before the lentils and potato are tender.
5. Check a sweet potato cube with a fork and taste a cooled spoonful of lentils. Continue cooking if either remains firm. Mash a few cubes against the pot for a thicker texture, or leave everything as it is.
6. Taste before adding salt, particularly with salted broth. Finish with a little lemon juice if you want a brighter flavour.

The soup thickens as it stands. Judge its final consistency after a brief rest, especially if you are preparing it ahead.

Which lentils should you use?

Split red lentils: The intended choice here. They break down as they cook and help thicken the broth.

Brown or green lentils: These tend to keep more of their shape and may need additional simmering time and liquid. Check tenderness rather than treating the red-lentil timing as a guarantee.

Canned lentils: Drain and rinse them. Simmer the sweet potato in the seasoned broth first, then add the cooked lentils near the end to heat through. Start with less broth because canned lentils will not absorb liquid like dried lentils.

For another interpretation, the Heart Foundation’s sweet potato and lentil soup uses green lentils and explains the texture difference when changing varieties.

Serving ideas and easy adjustments

Serve with bread, a small salad or a spoonful of plain yogurt if dairy suits your meal. Stir a handful of washed spinach into the hot soup at the end and let it wilt before serving.

For more vegetable-based bowls, explore my soup collection. If you prefer a roast-vegetable flavour, the roasted cauliflower and carrots make a useful side for a different meal.

Storing and reheating

Divide leftovers into shallow containers and refrigerate promptly. Use refrigerated soup within 3–4 days. When reheating, stir in water to loosen it and bring the soup to a rolling boil. This follows USDA guidance for leftovers.

Freeze individual portions if you will not finish it in that time. Label containers with the date, leave room for expansion, and thaw in the refrigerator or reheat from frozen in a saucepan, stirring as it melts.

Why are my lentils still firm?

They may need more time. Keep enough liquid in the pot for a gentle simmer and check the packet guidance. Lentil age and variety can change cooking time.

Do I need a blender?

No. Red lentils naturally soften into the broth. A spoon or masher is enough if you want to break up some of the sweet potato.