- 6 tablespoons (1 stick) unsalted butter
- 1 medium onion, peeled and thinly sliced
- 1 large bulb fennel
- 1 large celery root (about 1 pound)
- 4 cups chicken broth, homemade or store-bought, preferably organic
- Kosher salt and ground white pepper, to taste
- Fennel leaves, for garnish
- 2 tablespoons Pernod or any pastis-type liqueur
- ½ cup heavy cream
- In a large soup pot over medium-high heat, melt the butter and sauté the sliced onion, stirring intermittently, until it is soft and golden, about 10 minutes.
- While the onion is sautéing, cut the vegetables. Trim the feathery tops off the fennel bulb and set a few leaves aside for garnish. Cut the trimmed bulb in half lengthwise, then cut each hemisphere into ½-inch slices. With a sharp knife, peel the celery root and cut it into 1-inch cubes.
- Add the sliced fennel and cubed celery root to the pot and pour the chicken broth over them. When the soup comes to a boil, reduce the heat to low and simmer until the celery root and fennel are very tender, about 20 minutes. Purée the soup in small batches in the blender. Add salt and white pepper to taste, and keep warm.
- Just before serving the soup, make the Pernod cream. In a saucepan over high heat, warm the Pernod, then light it and burn off some of the alcohol (caution—flames!). Pour in the cream and bring the liquid to a full rolling boil, stirring to prevent the cream from boiling over. Boil the cream for 1 or 2 minutes, or until it is slightly reduced and beginning to thicken. Drizzle some of the cream on top of each serving of soup and garnish with the reserved fennel leaves.