Classic French Potato Leek Soup

Name: Classic French Potato Leek Soup
Prep time: 25 min
Cook time: 35 min
Total time: 1 h
Yield: 6 servings
Cuisine: French
Ingredients: 4 tablespoons (57 g) unsalted butter, cut into pieces; 1¾ pounds (about 4 medium leeks) (800 g) leeks, white and pale green parts only, halved lengthwise, sliced ¼-inch (6 mm) thick, and washed well in water then drained; 2 cloves (8 g) garlic cloves, thinly sliced; 1½ teaspoons (8 g) kosher salt, plus more to taste; 1½ pounds (about 4 medium) (680 g) Yukon Gold potatoes, peeled and cut into ¾-inch (2 cm) cubes; 4 cups (950 ml) low-sodium chicken or vegetable broth, at room temperature or warm; 1 leaf (1 g) bay leaf, dried; 3 sprigs (3 g) fresh thyme sprigs, whole; ½ cup (120 ml) heavy cream, at room temperature; ¼ teaspoon (½ g) white or black pepper, freshly ground, plus more to taste; 2 tablespoons (6 g) fresh chives, thinly sliced, for garnish (optional)

From the MyKitchenBank Kitchen

A silky, velvety soup built on sweet, gently softened leeks and buttery Yukon Gold potatoes, blended smooth and finished with a splash of cream. Simple, elegant, and deeply comforting.

Prep: 25 min
Cook: 35 min
Wait: 5 min
Total: 1 hr 5 min
Makes: About 7 cups (1.7 liters), serving 6 as a starter or light main

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Ingredients

6 servings

4 tablespoons (57 g) unsalted butter, cut into pieces
1¾ pounds (about 4 medium leeks) (800 g) leeks, white and pale green parts only, halved lengthwise, sliced ¼-inch (6 mm) thick, and washed well in water then drained
2 cloves (8 g) garlic cloves, thinly sliced
1½ teaspoons (8 g) kosher salt, plus more to taste
1½ pounds (about 4 medium) (680 g) Yukon Gold potatoes, peeled and cut into ¾-inch (2 cm) cubes
4 cups (950 ml) low-sodium chicken or vegetable broth, at room temperature or warm
1 leaf (1 g) bay leaf, dried
3 sprigs (3 g) fresh thyme sprigs, whole
½ cup (120 ml) heavy cream, at room temperature
¼ teaspoon (0.5 g) white or black pepper, freshly ground, plus more to taste
2 tablespoons (6 g) fresh chives, thinly sliced, for garnish (optional)

Equipment (6)

5- to 6-quart (4.7–5.7 L) heavy-bottomed pot or Dutch oven with lid
Large bowl for washing leeks
Sharp chef's knife and cutting board
Immersion blender or countertop blender
Wooden spoon
Ladle

Steps

Before you start

Leeks hide grit between their layers, so plan to slice them first and then wash them thoroughly in a bowl of water.
Use only the white and pale green parts of the leeks; the dark green tops turn bitter and tough in this soup (save them for stock).
If using a countertop blender, never fill it more than half full with hot soup and vent the lid, or hot steam can force the lid off.
Taste and season at the end; broths vary a lot in saltiness.

1
Clean the leeks
- Trim the roots and dark green tops from the leeks.
- Halve the white and pale green parts lengthwise and slice crosswise ¼ inch (6 mm) thick.
- Swish the slices in a large bowl of cold water, let the grit sink for 1 minute, then lift the leeks out with your hands or a slotted spoon and drain well.
- Peel and cube the potatoes and slice the garlic.
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Ready when: Leeks look clean and no grit remains at the bottom of the bowl.
Tip: Lift leeks out rather than pouring the bowl into a colander, or the grit goes right back on them.
2
Sweat the leeks
- Melt the butter in the pot over medium-low heat.
- Add the leeks and 1½ teaspoons salt and stir to coat.
- Cover and cook, stirring every 2 minutes, for 10 minutes.
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Ready when: Leeks are very soft, wilted, and glossy, with no browning.
Tip: If the leeks start to brown, lower the heat; browned leeks make the soup taste bitter and look tan.
3
Add the garlic
- Stir in the garlic and cook uncovered for 1 minute, stirring constantly.
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Ready when: Garlic smells fragrant but has not colored.
4
Add potatoes and broth
- Add the potatoes, broth, bay leaf, and thyme sprigs.
- Raise the heat to high and bring to a boil, which takes about 6 minutes.
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Ready when: Liquid is bubbling steadily across the surface.
5
Simmer until tender
- Reduce the heat to medium-low, partially cover, and simmer gently for 15 to 18 minutes.
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Ready when: A potato cube crushes easily against the side of the pot with a spoon.
Tip: Stir once or twice so nothing sticks to the bottom.
6
Remove the herbs
- Take the pot off the heat.
- Fish out the bay leaf and the thyme sprigs (the leaves will have fallen off into the soup) and discard them.
- Let the soup cool for 5 minutes so it is safer to blend.
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Ready when: Soup is no longer actively bubbling.
7
Blend until smooth
- With an immersion blender, purée right in the pot for 2 to 3 minutes, moving it around, until completely smooth.
- Or blend in batches in a countertop blender, filling it no more than half full, removing the center cap of the lid, and covering the opening with a folded towel.
- Return the soup to the pot.
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Ready when: Soup is velvety with no visible flecks of leek or lumps of potato.
Tip: Don't over-blend beyond smooth; overworked potato starch can turn gluey.
8
Finish with cream
- Set the pot over low heat.
- Stir in the cream and pepper and warm for 2 to 3 minutes without letting it boil.
- Taste, then add more salt and pepper as needed.
- If the soup is too thick, stir in broth or water, ¼ cup (60 ml) at a time.
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Ready when: Soup is steaming hot and coats the back of a spoon lightly.
Tip: Boiling after adding cream can make the soup taste flat and may cause it to separate.
9
Serve
- Ladle the soup into warmed bowls and sprinkle with sliced chives and a little extra pepper.

Good to know

Tips

Slice the leeks evenly so they soften at the same rate.
For an ultra-silky texture, pass the blended soup through a fine-mesh sieve.
Season in two stages: salt the leeks early for flavor, then adjust at the end after the cream is in.
To serve it chilled as vichyssoise, cool the finished soup completely and refrigerate for at least 4 hours, adding a little extra cream and salt before serving.

Make ahead

"Make the soup through step 7 (blended, before adding cream) up to 3 days ahead. Cool completely, refrigerate, then reheat gently and stir in the cream just before serving."

Storage & reheating

"Room temperature: no more than 2 hours. Fridge: up to 4 days in an airtight container. Freezer: up to 3 months, best frozen before the cream is added. Reheat in a pot over low heat, stirring often, until steaming (do not boil), thinning with a splash of broth or water if it has thickened."

Substitutions

heavy cream → whole milk, half-and-half, or full-fat coconut milk. Milk gives a lighter soup; coconut milk adds a subtle sweetness and keeps it dairy-free.
unsalted butter → extra-virgin olive oil. Use 3 tablespoons (45 ml) for a dairy-free version; flavor will be less rich.
Yukon Gold potatoes → russet potatoes. Russets give a slightly thicker, fluffier body; Yukon Golds are creamier and more forgiving.
low-sodium chicken or vegetable broth → vegetable broth. Makes the soup vegetarian; choose a mild, low-sodium one so it doesn't overpower the leeks.