Ingredients

  • 3 tablespoons extra-virgin olive oil, plus more for garnish
  • 1 cup thinly sliced leek (about 1 medium), white and light green parts only
  • 2 1/2 pounds celery root, also known as celeriac (about 3 medium), peeled and cut into 1-inch chunks
  • 12 ounces Yukon Gold potatoes (about 2 large), peeled and cut into 1-inch chunks
  • 1 medium tart apple, such as Granny Smith, peeled, cored, and cut into 1-inch chunks
  • 2 medium garlic cloves, peeled and smashed
  • 2 teaspoons kosher salt, plus more as needed
  • Freshly ground black pepper
  • 3 cups water
  • 2 cups low-sodium chicken or vegetable broth

Method

  • Heat oil in a large saucepan with a tightfitting lid over medium-high heat until shimmering.
  • Add leek and cook, stirring occasionally, until softened and translucent, about 3 minutes.
  • Add celery root, potatoes, apple, garlic, salt, and a pinch of pepper.
  • Stir to coat vegetables with oil, add water and broth, and bring to a boil.
  • Cover, reduce heat to low, and simmer until vegetables just give way when pierced with a knife, about 20 to 25 minutes.
  • Remove 1 cup of liquid from the saucepan; set aside.
  • Using a blender, puree the soup in batches until smooth, removing the small cap from the blender lid (the pour lid) and covering the space with a kitchen towel (this allows steam from the hot soup to escape and prevents the blender lid from popping off).
  • Once blended, transfer the soup back to the saucepan and keep warm over low heat.
  • If the soup is too thick, add the reserved liquid a little at a time until the soup reaches the desired consistency.
  • Taste and season with additional salt and pepper as needed.
  • To serve, drizzle with olive oil.