French Leek Soup with Potatoes: A Cozy Classic

French leek soup is a comforting, gently savory soup of softened leeks and potatoes simmered in broth, then blended until smooth or left slightly chunky. It is served hot, often with a little cream and fresh herbs; family and regional versions vary, and this straightforward potato-rich style is easy to adapt.

Ingredients

3 large leeks, about 1½ lb (680 g) trimmed and cleaned
3 tablespoons unsalted butter (42 g)
1 tablespoon olive oil (15 ml)
1 medium yellow onion, about 1 cup chopped (150 g)
2 garlic cloves, minced (about 6 g)
1½ lb Yukon Gold or other all-purpose potatoes, peeled and cut into ¾-inch (2 cm) pieces (680 g)
6 cups low-sodium chicken or vegetable broth (1.4 L)
1 bay leaf
½ teaspoon dried thyme (1 g), or 1 teaspoon fresh thyme leaves (1 g)
1 teaspoon fine salt (6 g), plus more to taste
¼ teaspoon freshly ground black pepper (about 0.5 g), plus more to taste
½ cup heavy cream (120 ml), optional
1 teaspoon lemon juice (5 ml), optional
2 tablespoons chopped chives or flat-leaf parsley (about 6 g), for serving

Instructions

Clean and prepare the leeks. Trim off the root ends and the dark, tough green tops, leaving the white and pale green parts. Slice the leeks lengthwise, then cut them crosswise into thin half-moons. Place the pieces in a large bowl of cold water and swish them apart with your fingers. Let grit sink, lift the leeks out rather than pouring the bowl through a strainer, and repeat with fresh water until no sand remains. Drain well. Leeks trap soil between their layers, so this washing step matters even if they look clean.
Soften the vegetables. Melt the butter with the olive oil in a large heavy pot or Dutch oven over medium-low heat. Add the sliced leeks and chopped onion, then stir to coat. Cook for 8–10 minutes, stirring every couple of minutes, until soft and glossy but not browned. If the vegetables begin to stick or color, lower the heat and add a tablespoon or two of water. Stir in the garlic and thyme and cook for about 30 seconds, just until fragrant.
Add the potatoes and broth. Tip in the potato pieces, broth, bay leaf, salt, and pepper. Stir, scraping the bottom of the pot to loosen any softened bits. Raise the heat and bring the liquid to a gentle boil, then lower the heat so it simmers steadily. Avoid a vigorous boil, which can break the potatoes apart before they cook evenly and make the soup splatter.
Simmer until tender. Partially cover the pot and simmer for 25 minutes, stirring once or twice. The potatoes should be easily pierced with the tip of a knife and the leeks should be very tender. If the pieces are still firm, continue simmering for a few minutes and check again. Remove the bay leaf before blending.
Blend to the texture you like. For a silky soup, use an immersion blender directly in the pot, keeping the blade fully submerged to avoid splashes. Blend in short bursts until smooth. Alternatively, carefully transfer the soup in batches to a countertop blender; do not fill it more than halfway, vent the lid, and cover the opening with a folded kitchen towel to let steam escape. For a rustic texture, blend only about half the soup and stir it back into the pot.
Finish and season. Stir in the cream, if using, and warm the soup over low heat for about 5 minutes without letting it boil. Taste and adjust the salt and pepper. A teaspoon of lemon juice can brighten the flavor; add it gradually, tasting as you go. Serve hot with chopped chives or parsley.

Tips

Wash leeks after slicing. Soil often hides inside the layers, so rinsing whole leeks under a tap may miss grit. Letting the cut pieces float in a bowl makes it easier for sand to fall to the bottom; lift the leeks out before draining.
Keep the leeks pale and sweet. Cook them gently rather than browning them. Browning adds a deeper, more toasted flavor that can overwhelm the mild leek-and-potato character. If the pot gets too hot, turn down the burner and add a small splash of water.
Choose the right potato and blend carefully. Yukon Gold potatoes give the soup a naturally creamy body. Russets also work, though they can make a blended soup more starchy or gluey if processed for too long. Blend just until smooth, not for several minutes.
Adjust dairy and broth to suit. Use vegetable broth for a vegetarian version, and omit the cream or replace it with unsweetened oat cream for a dairy-free bowl. The non-dairy option can taste slightly sweeter, so add it a little at a time and recheck the seasoning. If the finished soup is thicker than you like, stir in warm broth or water.

Serving Suggestions

Serve the soup in warm bowls with a scattering of chives, parsley, or thinly sliced green leek tops that have been washed well. A small drizzle of cream or olive oil adds a neat finish, while black pepper gives the mild broth a little lift. Keep garnishes modest so the gentle sweetness of the leeks remains easy to taste.

Crusty bread, a baguette, or toasted sourdough is useful for dipping and makes the soup a more substantial lunch. For a fuller meal, pair it with a green salad dressed with vinaigrette, or serve a smaller bowl before a simple roast chicken or vegetable tart. If offering toppings, set them out separately so each person can choose: crisp croutons, extra herbs, or a little grated cheese all work without changing the soup itself.

Variations

Make a lighter, broth-forward soup. Leave out the cream and blend only part of the pot, or skip blending and serve it as a clear, chunky soup. The leeks and potatoes will still thicken the broth slightly, and a little chopped parsley or lemon juice can keep the flavor lively.

Make it fully vegetarian. Choose vegetable broth and check that it is not overly salty. A good vegetable broth keeps the soup savory without masking the leeks. For a vegan bowl, replace the butter with another tablespoon of olive oil and omit the cream or use an unsweetened plant-based alternative.

Try a chilled version. For a soup inspired by vichyssoise, make the recipe with vegetable or chicken broth, blend it completely smooth, and chill it until cold. Stir well before serving and thin with a little cold broth if it has thickened in the refrigerator. Chilled leek-and-potato soups have different proportions and traditions, so consider this a simple cool variation rather than a single definitive version.

Add a gentle aromatic note. Replace the thyme with a small pinch of nutmeg, or add a few parsley stems to the broth while it simmers and remove them before blending. Avoid adding several strong herbs at once; the soup is at its best when the leek flavor stays at the center.

Storage and Reheating

Refrigerate leftovers within 2 hours of cooking. For faster cooling, divide the soup among shallow containers rather than leaving a large, hot pot on the counter. Cover and refrigerate for 3–4 days. If you made a large batch, freeze portions in airtight freezer-safe containers, leaving a little room at the top for expansion; use within about 2–3 months for best quality. Thaw frozen soup overnight in the refrigerator.

Reheat only the portion you plan to eat in a saucepan over medium-low heat, stirring often, until steaming throughout. Leftovers should reach 165°F (74°C), the USDA FSIS safe reheating temperature; check with a food thermometer. Avoid a hard boil, especially if the soup contains cream, because it can affect the texture. If it has thickened during storage, add a splash of broth or water as it warms. Cream-based soups may separate slightly after freezing; whisk or stir as they reheat to bring them back together.

Frequently Asked Questions

Do I use the green parts of leeks?

Use the white and pale green portions, which soften readily and have a mild flavor. The dark green tops are tougher and more fibrous, so trim them away for this smooth soup. You can save clean dark greens for vegetable stock, but they are not needed in the recipe.

Can I make French leek soup without a blender?

Yes. Leave the soup chunky, or mash some of the cooked potatoes against the side of the pot with a spoon or potato masher to thicken the broth. The result will be less silky but still comforting. If you want a smoother texture without an immersion blender, use a potato masher thoroughly or pass the soup through a food mill.

Why does my leek soup taste gritty?

Grit usually means sand remained between the leek layers. Slice the leeks first, then swish them in a bowl of cold water and lift them out so the dirt stays at the bottom. If the soup is already cooked and you notice grit, carefully strain it through a fine-mesh sieve, rinse the pot, and return the soup to the pot before serving.

Can I make the soup ahead?

Yes. Prepare it through blending, cool it promptly, and refrigerate it for up to 3–4 days. For the freshest dairy texture, wait to add the cream until you reheat the soup, then warm it gently. The flavor often seems more blended after a night in the refrigerator, so taste again and adjust salt, pepper, or lemon before serving.

What can I use instead of heavy cream?

You can omit it for a lighter soup; the potatoes already provide body. For a dairy-free finish, use unsweetened oat cream or another neutral plant-based cream. Whole milk can also work, though it makes the soup less rich and is more prone to curdling if boiled, so stir it in over low heat and do not let the pot boil.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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