This Irish Potato Leek Soup is creamy and decadent and uses only FOUR ingredients – potatoes, leeks, broth, and plenty of butter – with no cream or milk! It’s cheap, comes together in 30 minutes, and is a beautifully simple recipe for St. Patrick’s Day or early spring, when leeks are in season and the weather is still cool.
Even though this soup has a creamy texture, it has NO milk or cream- just leeks, potatoes, chicken stock, and plenty of good, salted, Irish butter.
And it’s very easily adaptable to be vegetarian or even vegan by using vegetable stock and olive oil instead of butter, and dairy free with ghee.
But I do recommend, strongly, using really good quality salted Irish butter for this. I’m almost an exclusive Kerrygold butter user, and it was perfect in this soup. So perfect, in fact, that I used an entire stick (8 tablespoons) of it *gasp!* TRUST ME ON THIS!
Ingredients and Substitutions
- Russet Potatoes – I do recommend russet because they are the starchiest and do well in this soup, but white potatoes will also do OK here.
- Butter – preferably Irish, salted butter, such as Kerrygold. Ghee, vegan butter, or olive oil may be used for a dairy-free version (see more on this below).
- Chicken broth – or vegetable broth, for a vegetarian option.
- PLENTY of salt and pepper
- Optional toppings: chives, sour cream, and/or bacon for serving on top of the soup.
Do I really need a whole stick of butter for this recipe?
No. You don’t. You can easily take it down to 4 tablespoons (1/2 a stick) or even just two, if you really want to lighten things up.
But it’s SO good with the butter. Butter sometimes has people scurrying away, but the same people often add heavy cream, oil, or other fat-laden ingredients to recipes without batting an eye.
There are other potato leek soup recipes that use heavy cream (up to a cup of it) along with butter. I chose to just use the butter and really let it shine.
First of all, the salt in salted butter helps season the entire thing. The richness of the flavor gets in every bite, and all the delicious fat coats every morsel of the starchy potatoes (which also helps it freeze well!). It also helps soften the leeks to meltingly-tender perfection.
So no, you don’t HAVE to, but I recommend using a full 1/2 cup or 8 tablespoons of butter (and when I say “stick” of butter, I mean a standard stick- Kerrygold comes in portions that are actually a full cup, so keep that in mind if you use it!).
How do I wash and prep the leeks?
Leeks are delicious, but require some finesse when it comes to prepping them.
If you’ve ever used them before, you know that they often are pretty dirty. The dirt they grow in gets in all the layers of the leeks. So it’s really important to clean them properly.
Here’s a foolproof method for cleaning leeks. First, trim the dark green parts off. Then, halve them lengthwise, and slice them thinly, into about 1/4 inch pieces.
Place all those slices in a large container and cover them with a LOT of water. Then, use your hands to separate out all the pieces of the leeks and stir them around a bit, loosening any dirt that’s clinging to them.
The dirt will sink to the bottom of the container. Use a slotted spoon to remove the leeks to a colander, since pouring them out into the colander would just redistribute all that dirt on top of them. Then, give them one final rinse when they’re in the colander.
Now you’re ready to use them! You can do this a couple of days in advance if you want and keep the prepped leeks in a container in the fridge until you’re ready to use them.
Can I freeze this potato leek soup or make it ahead of time?
Normally, potatoes can’t be frozen because their texture gets ruined.
But because of the high fat content in this soup, you can absolutely freeze it! Same goes with mashed potatoes, as long as there’s a lot of fat in them.
This is a great recipe to make ahead of time- it reheats wonderfully. You can keep it in an airtight container in the freezer for up to 6 months or in the fridge for up to about 5 days.
How do I get this soup to be so smooth and creamy?
I used an immersion blender – one of my all-time FAVORITE kitchen tools – to puree this soup and get it to a velvety smooth consistency right in the pot.
An immersion blender is like a magic wand you can stick directly in the soup pot to puree it. It’s faster and simpler than using a standing blender and it does a great job at making it silky smooth. Plus, it’s WAY easier to clean than a normal blender!
You can even use an immersion blender to make single serve smoothies by pureeing all the ingredients directly in your jar or cup or whatever you plan on drinking the smoothie out of.
If you don’t have an immersion blender, you can absolutely use a standing blender to puree this potato leek soup in batches. Be careful, since it’s hot!
Can I make the potato leek soup lumpy instead of smooth?
Sure! For a more rustic, chunky potato leek soup, you can just use a potato masher to break up the potatoes at the end after they’ve cooked.
Can I make a dairy-free or vegan potato leek soup?
Sure! Just use a dairy-free butter substitute, such as vegan butter, olive oil (in a lesser quantity- see recipe notes), or ghee (not vegan, but dairy-free).
How to serve potato leek soup
I recommend topping this soup with some chopped chives, fresh cracked black pepper, and a little bit of sour cream. I thinned my sour cream out a little with milk to get that pretty swirl you see in the photos (but when I served it later for my family I just dolloped some on). You can also top it with chopped bacon- yum!
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Irish Potato Leek Soup
- 8 tablespoons butter divided, preferably Irish salted butter, such as Kerrygold
- 3 large leeks white and light green parts only, halved and sliced, washed thoroughly (see notes)
- 2 – 2½ pounds russet potatoes about 3 medium potatoes, peeled and diced
- 4 cups chicken stock/broth or vegetable broth for a vegetarian version
- kosher salt to taste
- black pepper to taste
- chopped chives, bacon, and/or sour cream for serving (optional)
- Melt 6 tablespoons of the butter in a large pot over medium heat.
- Add the leeks, stir to coat in the butter. Cook for approximately 10 minutes over medium heat, stirring occasionally but not too frequently, until the leeks are meltingly tender and soft. You don't want them to brown- if they are browning, turn down the heat.
- While the leeks are cooking, peel and dice the potatoes (2 lbs.) into 1/2" pieces. Tip: The smaller the pieces are diced, the shorter time the soup will take to cook.
- After the leeks are cooked, add the peeled and diced potatoes, chicken broth (4 cups), and some kosher salt and black pepper. Use more salt if you are using unsalted butter and/or low sodium chicken stock. Bring to a boil.
- Cover, turn the heat to low, and simmer for 10-15 more minutes, until potatoes are cooked through (use the tines of a fork to test the potatoes – if they pierce them very easily, the potatoes are done).
- Use an immersion blender to puree the soup directly in the pot. Alternatively, you can blend it in batches using a standing blender, or you can use a potato masher for a more rustic, lumpy texture.
- Turn off heat and stir in the remaining 2 tablespoons of butter until melted. Taste and adjust seasoning if necessary. Tip: Don't be shy with the salt – this soup needs plenty of it!
- Serve topped with chopped fresh chives, cracked black pepper, crumbled bacon, and/or sour cream, if desired.
- Time saving tip: If you don’t care about super smooth soup, I recommend using white potatoes. You can keep the skin on, since it’s thinner, so you won’t have to worry about peeling them. Just give them a good wash with a scrubbing brush.
- Don’t skimp on the salt! Potatoes are bland and need a lot of it. I didn’t include the exact amount since it will vary depending on the broth and butter you use, so you’ll have to taste and adjust according to your preference. But if you think it’s a bit bland, chances are, you just need to add some salt.
- To wash the leeks, trim the dark green parts off. Then, halve them lengthwise and slice them into 1/4″ pieces. Place all the cut leeks into a large container and cover with cold water. Use your hands to separate the leeks out as much as possible. Then, use a slotted spoon to lift them out of the water and transfer them to a colander (the dirt will sink to the bottom of the container). Give them one final rinse in the colander and you’re good to go!
- A note on the butter: While I recommend using butter with abandon here, you can make a lighter version by using 4 tablespoons, or even 2 tablespoons, of butter if you want. If you do this, I recommend adding some half and half or whole milk at the end to make it a little richer and creamier.
- To make this dairy free, just use ghee instead of butter.
- To make this vegetarian, make sure to use vegetable stock instead of chicken.
- For a vegan option, you can use 2 tablespoons of olive oil in place of the butter, then stir in 2 more tablespoons at the end after cooking.
- Freeze in an airtight container for up to 3 months.
Nutrition Information Disclaimer
The provided nutrition information is my best estimate and does not include any added sodium from seasoning to taste, any optional ingredients, and it does not take brands into account. I use an automatic API to calculate this information. Feel free to calculate it yourself using one of these tools: