Cauliflower Potato Leek Soup

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This cauliflower potato leek soup is a satisfying and hearty dish that won't weigh you down. The cauliflower creates a rich, creamy texture and eliminates the need for heavy cream or cheese.

cauliflower leek potato soup in bowl with spoon and napkin

I love potato and leek soup because it's easy to make and takes only a handful of simple, whole ingredients. While this version has an extra step - roasting cauliflower - it's worth the effort for the extra nutrients, vegetables, and heartiness.

While the recipe does contain butter, you can easily substitute it with an alternative and make it completely dairy-free and vegan.

I make some kind of soup just about every week and if you enjoy soup as much as I do, check out some of my other recipes, such as this tasty seafood newburg soup, a filling lentil and rice soup, and another variation on the classic leek potato soup, a celery and leek soup. Or if you like mushrooms, you'll want to try this Potato and Mushroom Soup.

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🥔Ingredients
🔪Instructions
🥄Substitutions and Variations
🍲Equipment
🥡Storage
🧂FAQ
🍕 Pairing
📖 Recipe
🍲 Related
💬 Comments

🥔Ingredients

This soup takes just eight ingredients. No fancy spices or anything hard to find.

olive oil - your favorite variety works great
cauliflower - pick one that's creamy white, without blemishes
leeks - look for leeks that are firm, with dark green tops and white bottoms
butter - make it dairy-free and use more olive oil, if needed
garlic - what's a soup without a bit of garlic?
thyme - fresh is best, but dried will work
potatoes - Russet or a Yukon Gold
broth - vegetable or chicken, I look for low sodium since I like to salt food myself
optional toppings - such as crumbled bacon, cheese, or croutons

See the recipe card below for the quantities.

🔪Instructions

Let's make some soup.

cauliflower chopped up and on a baking sheet ready for roasting

Preheat the oven to 425 F. Roughly chop the cauliflower. Spread it on a baking sheet and toss with the oil and ½ teaspoon of salt. Roast for about 18 minutes.

leeks chopped, potatoes being peeled on cutting board with knife and peeler

Meanwhile, slice the white and light green parts of the leek, and peel and chop the potatoes. Mince the garlic and remove thyme leaves from the stems.

sliced leeks in a bowl of water with some being held in a hand

Give the leeks a good rinse and drain to remove any dirt or sand.

leeks being sauteed in a dutch oven with butter

In a Dutch oven, melt the butter. Add the leeks and saute until soft and creamy, about 10 minutes. Add the minced garlic, thyme, and ½ teaspoon of salt about halfway through.

potatoes and broth added to the soup pot

Add the potatoes and broth. Bring to a boil and simmer for about 10 minutes.

Stir in the roasted cauliflower and add a few grinds of fresh black pepper.

soup being pureed with an immersion blender

Off heat, use an immersion blender to carefully puree the soup until creamy.

Serve with your choice of toppings, such as bacon and additional thyme leaves.

Roasting the cauliflower may seem like an unnecessary step, but I think it really helps to add even more flavor. And if you can get it in the oven right off the bat, it'll be ready to go by the time the soup is ready to puree. So you're not really adding much extra time in the scheme of things.

But if you're in a rush and don't want to turn the oven on, fine. Just add it in with the potatoes. You'll still get the creamy texture in the end.

Hint: Soups are made all the better by their toppings. A few ideas for this one:

Chop a few slices of bacon and cook until crispy in a pan while the soup simmers.
Set aside some of the roasted cauliflower and use it as a topping.
Toss some cubed stale bread with a bit of oil and spices and cook them in a pan until browned and crispy for speedy croutons.
Shredded cheddar cheese will melt beautifully on top, if you don't mind a bit of dairy.
If you have extra thyme, but not time, a few small springs look great, if nothing else.

🥄Substitutions and Variations

A few ways to customize this cauliflower potato leek soup.

Dairy-free and vegan - Simply swap the butter for olive oil.
Dried thyme - Yes, dried thyme will work in place of fresh, though it likely won't add as much flavor. Use about a ⅓ as much.
Not roasting the cauliflower - If you can't be bothered to roast the cauliflower, add it to the pot when you add the potatoes and cook until tender.
Chunky version - You can actually skip the pureeing altogether if you don't want the soup creamy and just mash it up a bit with a potato masher. Though you won't get the benefit of the cauliflower's creaminess. I bet it would still be delicious, though.

🍲Equipment

There are two pieces of equipment that I think will make this soup easier, if not better.

First is a Dutch oven. I say it all the time, but a Dutch oven is a great investment. You don't need the high-end, (and yeah, overpriced) version, there are decent ones out there for about $50 and they'll last you for years. The heavy bottom helps prevent burning and retains heat well, not to mention they're great for going from the stovetop into the oven.

The second item is an immersion blender. Sure you could do this with a regular blender, but ladling soup into the blender is tedious, messy, and a bit dangerous if the soup is very hot. With an immersion blender, you can puree the soup right in the pot without having to wash a whole blender after. I recommend this one from Braun.

🥡Storage

Store leftover cauliflower potato leek soup in a container in the fridge for up to 4 days. I tend to store most of my leftovers in deli takeout containers like these.

🧂FAQ

Why is my potato leek soup gummy?

Make sure to cook the potatoes all the way through before pureeing. Also, don't go overboard pureeing the soup. It doesn't have to be perfectly smooth. If it seems too thick, thin it out with more broth.

Why is my leek and potato soup bland?

If you follow this recipe, it shouldn't be! But I have had bland leek and potato soups in restaurants, so I understand your concern. I think sometimes people just throw everything in a pot and boil it without taking the time to layer flavor by sauteing vegetables and seasoning first.

There aren't many ingredients here, so don't skip the salt, garlic, or thyme, as they add much to the flavor. Of course, taste your soup before serving and add more of those seasonings, if needed. And the worst case, if it's still bland, add a splash of acid, like vinegar, to boost the soup's flavor. Those toppings add flavor too, so definitely add a few of them if you feel something is lacking.

Is it OK to reheat leek and potato soup?

Of course! Do so in a small pot over low heat or loosely covered in the microwave until hot.