This vegan leek and potato soup is creamy, gently oniony, and finished with a big handful of peppery watercress that brightens every spoonful. It's simple enough for a weeknight, and it tastes even better the day after you make it.
Photos by Hannah Kaminsky.
Classic leek and potato soup usually leans on butter and cream, but you don't need either one here. Mashing some of the potatoes right in the pot thickens the broth naturally, and a splash of unsweetened rice milk makes it silky without weighing it down. The watercress goes in at the end, so it keeps its fresh, slightly spicy bite.
Key Ingredients & Substitutions
- Leeks. Use the white and palest green parts, which are the most tender and the sweetest. The dark green tops are tough, but you can save them for homemade vegetable stock. If you're short on leeks, a large sweet onion will work, though the soup will taste a little less delicate.
- Potatoes. Yukon Gold potatoes give the creamiest, most buttery texture, while russets break down more and make a thicker soup. Either works. Red potatoes hold their shape, so choose them only if you like a chunkier bowl.
- Vegetable bouillon. Bouillon cubes and water keep this recipe budget-friendly. We like Edward & Sons Garden Veggie bouillon cubes, which are vegan and gluten-free. You can also swap the water and cubes for about 5 cups of low-sodium vegetable broth.
- Watercress. Its peppery flavor is what makes this soup special. Baby arugula is the closest substitute; baby spinach works too, but it's much milder.
- Rice milk. Unsweetened rice milk is light and neutral. Unsweetened oat milk, soy milk, or almond milk are all good swaps. Just make sure it's unsweetened and unflavored.
Helpful Tips
Clean the leeks well. Leeks grow in sandy soil, and grit hides between the layers. Slice them first, then swish the slices in a big bowl of cold water. The dirt sinks to the bottom, so lift the leeks out with your hands or a slotted spoon rather than pouring them into a colander.
Cook the leeks low and slow. Keeping the pot covered over medium heat lets the leeks soften and turn sweet before they take on a little golden color. Rushing this step over high heat can scorch them and leave a bitter edge.
Mash only part of the potatoes. A roomy Dutch oven gives you space to press some of the potatoes against the side of the pot with a potato masher. That releases their starch and thickens the soup while leaving tender chunks behind. For a smoother soup, a few quick pulses with an immersion blender do the job; just don't overdo it, or the potatoes can turn gluey.
Keep it below a boil after adding the milk. Nondairy milks can separate if they boil hard. A gentle simmer over very low heat keeps the soup smooth.
Make it a day ahead. Like many soups, this one improves as it rests, because the leeks and potatoes have time to mellow and blend. If you're making it ahead, hold back the watercress and stir it in when you reheat, so it stays bright green.
Variations
- Extra creamy. Blend a quarter cup of soaked raw cashews with the rice milk before adding it for a richer, more velvety soup.
- Garlic and herb. Add 2 or 3 minced garlic cloves with the leeks, and a sprig of fresh thyme along with the bay leaf.
- Spring green. Stir in a cup of frozen peas or a handful of chopped asparagus during the last 5 minutes of simmering.
- Smoky. A half teaspoon of smoked paprika gives the soup a subtle, warming depth, especially nice on colder days.
- Protein boost. Add a can of drained, rinsed white beans with the milk to make the soup more filling.
Serving Ideas
This soup is hearty enough to be a light meal on its own, especially with some good bread for dunking. A slice of Quick Three-Grain Brown Bread or a square of Easy Vegan Cornbread rounds it out nicely.
For a fuller dinner, pair a bowl with a crisp salad. Leftover watercress is perfect in a Jicama Salad with Oranges and Watercress, or simply toss mixed greens with a 5-Minute Vinaigrette. Looking for more ways to cook with spuds? Browse our favorite vegan potato recipes.
Storing & Freezing
Let the soup cool, then refrigerate it in an airtight container for up to 4 days. It thickens as it sits, so add a splash of rice milk or water when you reheat it gently on the stovetop over low heat. Keep the garnish watercress separate and add it just before serving.
You can freeze this soup for up to 3 months, ideally before adding the fresh watercress garnish. Potatoes can turn a little grainy after freezing, so thaw the soup overnight in the fridge, then reheat it slowly and give it a good stir or a quick pulse with an immersion blender to bring back its creamy texture.
More Cozy Vegan Soups
If you loved this recipe, here are a few more you might enjoy:
- Vegan Lemony Leek and Mushroom Soup
- Cream of Corn and Watercress Soup
- Vegan Cream of Asparagus Soup
- Vegan Cream of Broccoli Soup
Recipe
Leek and Potato Soup with Watercress
Equipment
- Potato masher
Ingredients
- 1 ½ tablespoons olive oil
- 3 large leeks white and palest green parts only, sliced and rinsed well
- 4 large potatoes about 2 ½ pounds, peeled and diced
- 1 bay leaf
- 2 vegetable bouillon cubes gluten-free if needed
- 5 cups water or just enough to cover the potatoes
- 1 cup packed watercress leaves thick stems removed, roughly chopped
- 1 to 1 ½ cups unsweetened rice milk or other nondairy milk plus more as needed
- Salt and freshly ground pepper to taste
- 2 tablespoons chopped fresh parsley or more, to taste
- Watercress leaves for garnish
Instructions
- Heat the oil in a large soup pot or Dutch oven over medium heat. Add the leeks, cover, and cook for 8 to 10 minutes, stirring occasionally, until they're soft and just beginning to turn golden.
- Add the potatoes, bay leaf, bouillon cubes, and just enough water to cover the potatoes (about 5 cups). Bring to a boil, then reduce the heat to a gentle simmer. Cover and cook for 15 to 20 minutes, until the potatoes are very tender when pierced with a fork.
- Remove and discard the bay leaf. Mash some of the potatoes against the side of the pot with a potato masher or the back of a large spoon (or give the soup a few short pulses with an immersion blender) until it's thick and creamy but still a little chunky.
- Stir in the watercress and 1 cup of the rice milk. Simmer over very low heat, uncovered, for 10 minutes, stirring occasionally; don't let it come to a boil. Season to taste with salt and pepper.
- For the best flavor, let the soup stand off the heat for 1 to 2 hours, or let it cool and refrigerate overnight. Reheat gently over low heat, stir in the parsley, and thin with more rice milk if it's too thick. Taste and adjust the seasoning.
- Ladle into bowls and top each serving with a generous handful of fresh watercress leaves.
Susie says
I have a similar recipe which uses spinach as the green, and i spice it with tarragon, curry and a bit of soy sauce. i use soy milk, but find that it tends to curdle in the cooking. is rice milk less sensitive?? maybe i will try that next time. thanks Nava
Nava says
Susie, I much prefer the more neutral flavor of plain rice milk in soups. It doesn't curdle, and really blends nicely with all the flavors.
Rian says
I'm not a fan of leeks, but there are so many recipes I wish to try that use them. Is there a good alternative to leeks that provides the same texture?
Nava says
You can use ordinary onions (or red or Vidalia onions); though I wonder if it's the onion-y taste of leeks or just the texture...without any onion in the base, this simple, mild soup would be rather flat. Hope that helps!
Angie says
HI! I saw you on "Niki's Simple Life" meet and greet. Your photos are stunning! I've been blogging less than 6 months and my photos are definitely progressing, but I still have so much room to grow! Any suggestions? Do you use any online editing programs for your photos? Again, these look amazing!