A Silky Blended Sweet Potato Soup

An easy 40-minute soup, this lentil sweet potato soup is a great weeknight dinner. It’s a cosy cold weather soup made with sweet potato (or carrots, or pumpkin, or all three – see below), coconut milk, tomatoes, red lentils, and a warming mix of spices.

I like to make a big batch of this soup and freeze leftovers in jars for whenever I don’t have time or just don’t feel like cooking. It freezes really well and I almost always have a jar or two sitting in the freezer. It’s smooth and velvety, even with my old stick blender, and you really wouldn’t know that there are lentils in it.

We usually serve this with brown rice or a slice of sourdough. About the toppings – it’s nice to add a little colour and texture to break up the creaminess. I often serve it with rye croutons, or sunflower seeds and parsley, but this iteration is my favourite.

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Ingredients You’ll Need and Why

This is a simple recipe, with pantry staple ingredients and common spices. There are several good substitutions that can be made, outlined below. These are my notes from recipe testing. You can find the full recipe card below with complete measurements and instructions.

• Sweet potato: this can be made with only sweet potato but I often use a mix of sweet potato and carrot or pumpkin, depending on what’s on hand. Carrots can take a little bit longer to cook so keep that in mind. I don’t peel the sweet potato for this recipe but you can if preferred.
• Vegetable broth: if seasoned sufficiently, you can use water in place of broth for this recipe, which, if store-bought, is mostly just salt anyway.
• Red lentils: whole or split, but note that whole red lentils do take a few minutes longer to cook. You can soak the lentils in advance to decrease the cooking time.
• Coconut milk: full-fat coconut milk will add the most flavour, but light coconut milk can be used for this recipe. It will make the soup slightly thinner.
• Tomatoes: this can be whole, diced, or pureed tomatoes. I’m sure you could substitute an equal amount of fresh tomatoes, but I haven’t tried it.
• Spices: turmeric, coriander, and hot pepper. Change these up to suit what you like, or use a curry blend of some kind instead.

How to Make Sweet Potato Soup

The sweet potato is partly cooked before the broth is added, improving the flavour and reducing the boiling time, which helps to prevent the coconut milk from splitting.

Step 1: heat a large pot over low-medium heat, then add the oil. Add the onion and cook for about five minutes, stirring frequently, then add the ginger and garlic and cook for another three minutes. If the pot is too hot the onion will stick and brown. Reduce the heat and add a splash of water if needed.

Step 2: add the sweet potato and cook for another eight minutes, stirring frequently to prevent sticking. You can see here that I don’t peel the sweet potato. For this soup in particular, as it’s blended, you really don’t notice the skin.

Step 3: add the spices and cook for another minute, coating the vegetables. Adding the spices before the liquid helps to bloom them, improving flavour.

Step 4: add the lentils, broth, and coconut milk. Whole coriander seed might be too strong for some people, as it doesn’t blend completely with an immersion blender. If you don’t want to risk crunching on a coriander seed, grind it in a mortar and pestle first or use ground spices.

Related: Carrot Coriander Soup

Step 5: simmer for about 20 minutes, or until the lentils are very soft. This can take longer if the lentils you’re using are very old (and they might have already been old in the shop).

Step 6: blend until very smooth with an immersion blender, or cool to room temperature and blend in a standing blender. Serve hot.

Expert Tips for the Best Soup

• Season to taste: with any soup, it’s key to taste before serving and season as needed. Not only salt, but also for a sweet soup like this, you may need a splash of acid through a squeeze of lemon or a touch more vinegar.
• Use whole tomatoes: if you’re blending the dish in any case, whole tomatoes are usually better quality than diced or crushed canned tomatoes.
• Cool before blending: to use a standing blender rather than immersion, the soup should be cooled first unless your blender specifically states that it can be used for hot ingredients. An immersion blender is truly one of the best kitchen tools you can have, especially if you often make blended soups or things like homemade tomato sauce. We use ours for smoothies, soap making, cooking, and more. It’s stainless steel so I feel fine about using it for recipes that aren’t edible, like soap, and run it through the dishwasher.
• Try soaking: soaked lentils are ideal to add here as they cook faster and can be easier to digest. I soak a big batch in advance, then portion off to freeze to add to recipes like this.
• If the soup splits: don’t worry if the coconut milk splits slightly when brought to a boil. It will emulsify when you blend the soup.