The story behind this leek soup recipe? Coming in from the rain one evening in Geneva, Gourmet food editor Gina Marie Miraglia Eriquez was served a warm bowl of comfort—beautifully smooth and gently suggestive of leeks. Her version is velvety and luxurious but not at all heavy; dolloped with cool, billowy whipped cream, the soup coaxes out the vegetable’s most sensuous side.
Before you begin, wash your leeks with fervor—bits of grit tend to hide in each layer of these alliums. Lifting the chopped leeks out of the rinsing bowl after washing makes it more likely that any dirt will remain in the bottom of the bowl and not wind up in your pot. (You can also wash your leeks in a salad spinner and simply lift the insert up after cleaning the leeks.)
This is an ideal soup recipe for the still-cool days of spring, when leeks are especially sweet. Serve it in large warmed bowls with bread and salad for a cozy dinner, or offer smaller bowls as a starter for a more formal meal. If you’d prefer not to blend the soup in batches, you can also get it silky-smooth with the use of an immersion blender.
8 medium leeks (3 pound), trimmed, leaving white and pale green parts only, and chopped
1 medium onion, chopped
1 large carrot, chopped
2 celery ribs, chopped
1 teaspoon salt
½ teaspoon black pepper
1 stick (½ cup) unsalted butter
1 small boiling potato (6 ounces)
½ cup dry white wine
3 cups chicken stock or reduced-sodium chicken broth (24 fluid ounces)
3 cups water
1 Turkish bay leaf or ½ California
1½ cups fresh flat-leaf parsley leaves
¼ cup all-purpose flour
½ cup chilled heavy cream
Wash sliced leeks in a large bowl of cold water, agitating them, then lift out and drain well in a colander.
Cook leeks, onion, carrot, celery, salt, and pepper in 4 tablespoons butter in a 5- to 6-quart heavy pot over moderate heat, stirring occasionally, until softened, about 8 minutes. Peel potato and cut into ½-inch cubes, then add to onion mixture along with wine, stock, water, and bay leaf. Bring to a boil, then reduce heat and simmer, partially covered, until vegetables are tender, about 15 minutes.
Stir in parsley and simmer soup, uncovered, 5 minutes. Discard bay leaf and keep soup at a bare simmer.
Melt remaining 4 tablespoons butter in a 1-quart heavy saucepan over moderate heat, then add flour and cook roux, whisking, until golden, about 3 minutes. Remove from heat and add 2 cups simmering stock (from soup), whisking vigorously (mixture will be thick), then whisk mixture into remaining soup and return to a simmer, whisking.
Blend soup in 4 batches in a blender until smooth (use caution when blending hot liquids), about 1 minute per batch, transferring to a 3- to 4-quart saucepan. Reheat if necessary, then season with salt and pepper.
Beat cream in a bowl with an electric mixer at medium speed until it almost forms soft peaks. Serve soup topped with cream.
Soup is best when made 1 to 3 days ahead (to allow flavors to develop); do not whip cream ahead. Chill soup, uncovered, until completely cooled, then cover. Reheat, thinning with water if necessary.