Active Time

　　30 min

　　Total Time

　　1 1/4 hr

　　Silky smooth and with a crunchy topping, this seductive soup packs a range of flavors — earthy, smoky, and tart-sweet. If you decide to omit the bacon, substitute 1 tablespoon butter when you cook your vegetables.

　　

Ingredients

Makes 4 servings

　　3 medium leeks (3/4 lb), white and pale green parts only

　　3 bacon slices (2 oz)

　　1 tablespoon olive oil

　　1 1/2 lb celery root, peeled with a knife and cut into 1/2-inch pieces

　　3 cups water

　　1 3/4 cups reduced-sodium chicken broth

　　1 Granny Smith apple

　　3/4 celery rib, very thinly sliced on a long diagonal (1/2 cup)

　　1/3 cup inner celery leaves

　　1 teaspoon salt

　　1/4 teaspoon black pepper

　　1/2 cup half-and-half

　　

Special equipment:

Special equipment: an adjustable-blade slicer

　　

Step 1

Halve leeks lengthwise, then coarsely chop. Wash leeks in a bowl of cold water, agitating them, then lift out onto paper towels and pat dry.

　　

Step 2

Cook bacon in a 4-quart heavy pot over moderate heat, turning occasionally, until crisp, 6 to 8 minutes. Transfer to paper towels.

　　

Step 3

Pour off all but 2 teaspoons fat from pot, then add oil and cook leeks over moderate heat, stirring occasionally, until softened, about 6 minutes. Add celery root and cook, stirring, 2 minutes. Add water and broth and bring to a boil, then reduce heat and simmer, uncovered, until celery root is very tender, 35 to 40 minutes.

　　

Step 4

While soup simmers, thinly slice apple lengthwise into 1/8-inch-thick slices with slicer, working around core, then cut slices into 1/8-inch matchsticks with a knife. Gently toss with celery and celery leaves.

　　

Step 5

Purée soup in batches in a blender until smooth (use caution when blending hot liquids), transferring to a bowl. Return soup to cleaned pot. (If soup is too thick, thin with 1/2 to 3/4 cup water.) Stir in salt, pepper, and half-and-half and cook over moderately low heat, stirring occasionally, until warm. Season with salt, then divide among 4 bowls and top with apple-celery mixture and coarsely crumbled bacon.

　　Cooks' note:

　　Soup, without half-and-half, can be made 1 day ahead and cooled completely, uncovered, then chilled, covered. Reheat over moderately low heat, then add half-and-half and cook until heated through. Cool bacon completely, then chill, wrapped in paper towels in a sealed plastic bag. Recrisp in a preheated 300°F oven 6 to 8 minutes, or wrap in a paper towel and recrisp in a microwave 30 seconds to 1 minute. Prepare apple-celery mixture while reheating soup and recrisping bacon.