From NY Times; single batch makes 4 small servings, so double it if you plan to use it as a complete meal. The author says to puree this soup, using a blender—it makes for a much creamier soup than using either a food processor or immersion blender. Also, use a good quality stock—a vegetable stock recipe is included below.

2 ½ Tablespoons olive oil, divided
1 small leek, white part only, coarsely chopped
½ medium yellow onion, coarsely chopped
1 stalk celery, coarsely chopped
2 cloves garlic, sliced
1 pound peeled, chopped celeriac (from about 3 baseball-size bulbs)
3 cups mild chicken or vegetable broth, preferably homemade (see below)
½ teaspoon salt, plus more to taste
4-5 Tablespoons skim milk
Chopped chervil or parsley, for serving (optional)

In a large saucepan over medium heat, warm 2 Tbs olive oil. Add the leek, onion, celery, and garlic, and sauté until softened but not browned, stirring occasionally, about 5 minutes. Add the celery root, broth, and salt, and bring to a boil. Reduce the heat to low, partially cover, and simmer until the celery root is very tender. It should break apart easily when poked with a fork; on my stove, this takes about 35-45 minutes. Remove the soup from the heat.

Using a blender and working in small batches, purée the soup until very smooth. (Caution: when working with hot liquids, never fill the blender more than 1/3 full.) Return all soup batches to the saucepan and add the remaining ½ Tablespoon oil and the milk, and stir to incorporate. Taste, and adjust seasoning as necessary. Reheat gently until just steaming.

Yield: 4 dainty servings

Basic Vegetable Broth

1 ½ Tablespoon olive oil
1 medium onion, coarsely sliced
1 small leek, white part only, coarsely sliced
½ stalk celery, coarsely sliced
1 carrot, peeled and coarsely sliced
1 large clove garlic, peeled and smashed
8 cups cold water
1 bay leaf

In a large saucepan, warm the oil over medium heat. Add the onion, leek, celery, carrot, and garlic, and cook, stirring occasionally, until the onion is translucent, about 15 minutes. Add the water and bay leaf, and bring to a boil. Reduce to a simmer and cook, partially covered, until the vegetables are very soft, about 1 hour. Strain the broth through a sieve into a clean bowl or heatproof container, pressing down on the vegetables to extract all their juices. Let cool, uncovered. Refrigerate in a sealed container for up to a week, or freeze for longer keeping.

Yield: About 6 cups, give or take a little.