This Silky Leek and Potato Soup is classic French comfort food in a bowl. Leeks bring a gentle, sweet onion flavor, and the potatoes blend into a smooth, velvety soup without needing heavy cream.

It uses simple, cheap ingredients and comes together in about 45 minutes. Serve it with crusty bread for an easy dinner, or pack it for lunch all week.

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Why This Leek and Potato Soup Works

Leeks are milder and sweeter than regular onions. Cooking them slowly in butter until soft, without browning, keeps the flavor mellow and the color pale. A little onion and garlic add depth, and dried thyme gives a light herby note.

Potatoes do the heavy lifting for texture. As they simmer, they release starch. Once blended, that starch makes the soup thick and creamy on its own. A cup of milk or half-and-half at the end adds richness without making it heavy.

Ingredients and Easy Swaps

• Butter: Two tablespoons. Olive oil works for a dairy-free version.
• Leeks: Three medium leeks, white and light green parts only, cleaned and thinly sliced.
• Onion and garlic: One diced onion and 3 minced garlic cloves. A shallot is a nice swap for the onion.
• Potatoes: Two medium potatoes, peeled and cut into 1-inch cubes. Yukon Golds give the creamiest texture. Russets work too.
• Broth: Four cups of low-sodium chicken or vegetable broth.
• Milk or half-and-half: One cup. Use plant-based milk to make it vegan.
• Seasoning: Half a teaspoon of dried thyme, plus salt and white or black pepper. White pepper keeps the soup’s color clean.

How to Clean Leeks

Leeks grow in sandy soil, and grit hides between the layers. Cut off the dark green tops and the root end. Slice the leek in half the long way, then slice it into thin half moons. Put the slices in a big bowl of cold water and swish them around. The dirt sinks to the bottom. Lift the leeks out with your hands or a slotted spoon, and don’t pour them into a strainer, or the grit goes right back on top.

How to Make It at a Glance

1. Cook the leeks and onion: Melt the butter over medium heat. Add the leeks and onion and cook 6 to 8 minutes, until soft but not browned. Add the garlic and thyme and cook 1 minute.
2. Simmer the potatoes: Add the potatoes and broth. Bring to a boil, then simmer 15 to 20 minutes, until the potatoes are soft.
3. Blend: Puree with an immersion blender until smooth and velvety.
4. Finish: Stir in the milk or half-and-half. Warm gently but don’t let it boil. Season with salt and pepper.

Kitchen Tool Tips

• Chef’s knife: A sharp knife makes slicing leeks quick and clean.
• Immersion blender: It blends the soup right in the pot for a silky finish and less cleanup.
• Ladle with a pour spout: It makes serving easier and less messy.

Common Mistakes to Avoid

Browning the leeks. High heat makes them bitter and turns the soup brown. Keep the heat at medium and stir often.

Boiling after adding milk. Milk can curdle if it boils. Keep it at a gentle steam.

Under-seasoning. Potatoes soak up a lot of salt. Taste at the end and add salt a pinch at a time until the flavor pops.

Over-blending in a stand blender. Potatoes can turn gluey if blended too long at high speed. Blend just until smooth. If you use a regular blender, fill it only halfway and vent the lid.

Variations to Try

• Loaded baked potato style: Top each bowl with bacon, cheddar, sour cream, and green onions.
• Add greens: Stir a few handfuls of baby spinach into the hot soup before blending. It turns a pretty pale green.
• Make it heartier: Add diced ham or shredded rotisserie chicken after blending.
• Serve it cold: Chill the blended soup and serve it as vichyssoise, the classic French cold version. Thin it with a little extra milk.
• Brighten it up: Squeeze in a little lemon juice right before serving.

Nutritional Info (4 servings)

• Calories: 230
• Fat: 7 g
• Carbs: 30 g
• Protein: 6 g
• Fiber: 4 g
• Sodium: 580 mg

How to Serve

Serve hot with a drizzle of extra-virgin olive oil and chopped chives or parsley. It’s great with a simple green salad or toasted baguette slices. For a heartier bowl, top it with crumbled bacon, shredded cheddar, or a few croutons. A grilled cheese on the side makes it a meal kids love.

Storage

• Fridge: Up to 4 days in an airtight container.
• Freezer: Freeze in portions before adding the milk for up to 3 months. Stir in the milk when reheating.
• Reheating: Warm slowly on the stove and stir in extra broth if it’s too thick.

FAQs

Can I make this vegan?
Yes. Use olive oil instead of butter, vegetable broth, and an unsweetened plant-based milk.

Why are leeks better than onions here?
Leeks have a milder, sweeter onion flavor and a smoother texture once blended.

Can I add other vegetables?
Yes. Celery or fennel add extra flavor. Cook them with the leeks.

Can I leave it chunky?
Sure. Blend only half the soup, or mash it lightly with a potato masher for a more rustic texture.

Leftover Remix Idea

Use cooled leftover soup as the sauce for scalloped potatoes or a creamy leek and potato gratin. Pour it over thinly sliced potatoes, top with cheese, and bake until bubbly.