Leek Soup Recipe: Creamy Potato and Leek Soup from Scratch

This French-style leek and potato soup combines tender leeks, potatoes, thyme, and stock in a comforting bowl that can be blended silky smooth or left a little rustic. Often called potage parmentier, it is simple enough for a weeknight and works as a light meal or a starter; versions vary from home to home, especially in how much cream they use.

Ingredients

3 large leeks (about 750 g before trimming), white and pale green parts
1 medium yellow onion (about 150 g), peeled and diced
2 lb (900 g) Yukon Gold or russet potatoes, peeled and cut into ¾-inch (2 cm) pieces
3 tbsp unsalted butter (42 g)
1 tbsp olive oil (15 ml)
6 cups low-sodium vegetable or chicken stock (1.4 L)
1 tsp fresh thyme leaves (about 1 g), or ½ tsp dried thyme (about 0.5 g)
1 bay leaf
1 tsp fine salt (6 g), plus more to taste
¼ tsp ground white or black pepper (about 0.5 g), plus more to taste
½ cup heavy cream (120 ml), optional
2 tsp lemon juice (10 ml), optional
2 tbsp chopped fresh chives (about 6 g), for serving

Instructions

Clean and cut the vegetables, about 20 minutes. Trim off the leek roots and dark green tops, keeping the white and pale green sections. Split each leek lengthwise, slice it into thin half-moons, and rinse the slices thoroughly in a bowl of cold water, separating the layers so grit can fall to the bottom. Lift the leeks out rather than pouring the gritty water over them, then drain well. Dice the onion and peel and cut the potatoes into similar-sized pieces so they cook evenly. If you prefer a more rustic soup, you can leave the potato skins on after scrubbing them clean.
Soften the leeks and onion, 8 minutes. Melt the butter with the olive oil in a large heavy-bottomed pot over medium heat. Add the leeks, onion, salt, and pepper. Cook for about 8 minutes, stirring often, until the vegetables are soft and glossy but not browned. Lower the heat if the edges start to take on color; browned leeks can give the finished soup a sweeter, more roasted flavor than the delicate one intended here.
Simmer until the potatoes are tender, 20 minutes. Add the potatoes, stock, thyme, and bay leaf. Bring the liquid just to a boil, then reduce the heat to maintain a steady, gentle simmer. Partly cover the pot and cook for about 20 minutes, stirring once or twice, until a fork slides easily into the largest potato piece. Keep the simmer gentle rather than letting the soup boil hard, which can break up the potatoes unevenly and make the liquid reduce too quickly. Remove and discard the bay leaf.
Blend and finish, 7 minutes. For a smooth soup, use an immersion blender in the pot, moving it around until no large pieces remain. For a standard blender, work in batches and fill the jar no more than halfway; hot liquid expands, so vent the lid according to the blender’s instructions and cover it with a folded towel while blending. Return the soup to the pot if needed. Stir in the cream, if using, and warm gently for about 4 minutes without boiling. Add the lemon juice if you want a brighter finish, then taste and adjust the salt and pepper. For a partly chunky texture, blend only about half the soup and stir it back in. Ladle into bowls and top with chives.

Tips

Wash leeks carefully. Soil often hides between the layers, even when the outside looks clean. Slicing first and rinsing the separated pieces is more dependable than rinsing a whole leek. Drain them well so extra water does not dilute the flavor as they soften.
Choose potatoes for the texture you want. Yukon Gold potatoes give the soup a naturally creamy body and tend to hold their shape if you leave some pieces whole. Russets break down more readily and make a smooth blend feel thicker. Either works; cut the pieces evenly and check tenderness before blending.
Season after blending, too. Stock brands vary in saltiness, and potatoes absorb seasoning as they cook. Start with the listed salt, then taste the finished soup before adding more. A small amount of lemon juice can sharpen the flavor, but add it gradually so the soup does not become tangy.
Keep the heat gentle once dairy is added. Cream can separate or develop an unpleasant texture if the soup boils. Warm it slowly, stirring, and take the pot off the heat as soon as it is hot. For a dairy-free bowl, leave it out or use an unsweetened plant-based cream.

Serving Suggestions

Serve the soup hot in shallow bowls with chopped chives and a few turns of black pepper. A little cream swirled over each portion makes a simple garnish, while toasted bread or warm baguette gives the meal something crisp to contrast with the soft vegetables. For a fuller lunch, pair a bowl with a green salad dressed with vinaigrette; its fresh acidity balances the mellow leeks and potatoes.

It also works well as a first course before roasted vegetables, a baked fish dish, or a simple roast chicken dinner. If serving it to guests, keep the soup warm over very low heat and offer toppings separately so everyone can choose. Crisp croutons, extra chives, a few drops of olive oil, or a spoonful of sour cream are easy options. The soup thickens as it stands, so stir in a splash of stock or water if you want a looser consistency just before serving.

Variations

Make it dairy-free: Use olive oil instead of butter and skip the heavy cream. The potatoes still make the blended soup creamy. For a richer finish, stir in up to ½ cup (120 ml) unsweetened oat cream or cashew cream, checking that the product is unflavored and unsweetened. Coconut milk is another option, but its distinct flavor will make the soup less traditionally French in character.

Keep it chunky: Cut the potatoes into ½-inch (1.25 cm) pieces and simmer until tender. Mash a few against the side of the pot with a spoon to thicken the broth, leaving most of the vegetables intact. This avoids blender cleanup and makes a heartier bowl, though the broth will be less silky.

Add more vegetables or herbs: Stir in 1 cup (about 100 g) of chopped celery with the leeks for a more savory base, or add 1 cup (about 150 g) of peas during the final 3 minutes of simmering for a sweeter note. Parsley or a small amount of tarragon can replace the thyme, but add delicate herbs near the end so their flavor stays fresh.

Make a chilled version: For a vichyssoise-style variation, blend the soup smooth, add the cream, cool it promptly, and refrigerate until cold. This is a variation rather than a required step for the warm recipe. Taste it again before serving, since cold foods often need a little more salt or pepper to taste balanced.

Storage and Reheating

Cool the soup and refrigerate it within 2 hours of cooking. Store it in a covered container in the refrigerator for 3 to 4 days. If you know you will freeze some, it is best to set that portion aside before adding the cream; dairy can separate slightly after thawing, although blending or stirring may bring the texture back together.

Freeze soup in airtight, freezer-safe containers for up to 2 to 3 months for best quality, leaving a little room at the top for expansion. Thaw it overnight in the refrigerator or reheat it directly from frozen over low heat with a splash of stock or water. Reheat leftovers on the stovetop, stirring regularly, or in the microwave in short intervals, until the center reaches 165°F (74°C); check with a food thermometer. Avoid repeatedly cooling and reheating the whole pot: warm only the amount you plan to eat, and return the rest promptly to the refrigerator.

Frequently Asked Questions

Can I make leek and potato soup without a blender?
Yes. Leave the cooked vegetables in pieces for a clear, chunky soup, or mash some of the potatoes directly in the pot with a potato masher to thicken the broth. The result will have a more rustic texture than a fully blended version, but the flavor remains the same.

What part of the leek should I use?
Use the white and pale green parts for this recipe because they soften well and have a mild flavor. The dark green tops are tougher, but they need not be wasted: rinse them thoroughly and save them for stock, or slice them very thinly and cook them longer until tender.

Why is my soup too thick?
Potatoes absorb liquid, and the soup continues to thicken as it cools. Stir in warm stock or water a little at a time until it reaches the consistency you like, then taste and adjust the seasoning. Add the liquid before reheating if the soup has been stored overnight.

Can I use water instead of stock?
Yes, though the soup will taste milder. Use water and season carefully, or add a little extra thyme and a small amount of salt as it cooks. A good vegetable stock keeps the soup meat-free, while chicken stock gives it a more savory flavor.

Can I prepare the soup ahead?
Yes. Cook it through, cool it promptly, and refrigerate it for up to 3 to 4 days. For the freshest dairy texture, you can blend the soup and refrigerate it before adding the cream, then stir in the cream while reheating. Reheat to 165°F (74°C) and avoid bringing the cream-finished soup to a rolling boil.

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