Cream of Celery Root Soup with Celery Leaf Gremolata

6 tbsp unsalted butter
6 cups peeled, diced celery root (a 2 1/2 to 2 3/4 lb celery root) (see market note)
1 1/2 cups chopped onion
1 1/4 cups chopped celery, plus celery leaves for the garnish
7 1/2 cups chicken broth, plus more if needed
1/2 cup crème fraîche, plus 3 tbsp extra for the garnish
Kosher salt

Celery Leaf Gremolata
4 tbsp chopped celery leaves
4 tbsp toasted hazelnuts, coarsely chopped (see cooking tip)
4 tsp chopped flat leaf parsley
1 1/2 tsp grated lemon zest

1. In a large, heavy pot over medium heat, melt butter. When hot, add celery root, onion, and celery and sauté the vegetables, stirring, 3 to 4 minutes. Add broth, bring mixture to a simmer, and reduce heat to medium low. Cover and cook until vegetables are tender, 20 to 25 minutes.

2. Purée the soup in a food processor, blender or food mill. Or, use an immersion blender to purée the soup in the pot. Return the soup to the pot and stir in 1/2 cup crème fraîche. Taste soup and season generously with salt as needed. If soup is too thick, thin it with extra broth. (The soup can be prepared 2 days ahead. Cool, cover, and refrigerate. Reheat over medium heat, stirring often.)

3. For the gremolata, in a small bowl combine celery leaves, hazelnuts, parsley, and lemon zest and mix well. (Gremolata can be prepared 2 hours ahead; cover and refrigerate.)

4. To serve, ladle the soup into bowls and garnish the center of each with some gremolata and a small dollop of crème fraîche. Serves 6.

Market notes:
Celery root has a brown, gnarly exterior and creamy white flesh beneath. Use a sharp knife to remove the skin and any dark spots, then dice the flesh. Celery root has a more concentrated flavor than celery stalks, and is available in the produce section of many supermarkets. Store it in a plastic bag in the refrigerator.

Cooking tip: To toast hazelnuts, spread on a rimmed baking sheet and place in a preheated 350 degree F oven until lightly browned and fragrant, about 8 minutes. Watch carefully. Remove and place nuts in a kitchen towel and rub off as much of the skins as possible.

Copyright Betty Rosbottom 2016