This is an elegant and delicious soup that is perfect as a starter for Thanksgiving or a dinner party. This soup was derived from the mashed potatoes we have at my moms each Thanksgiving- they are always cut with a celery root puree, which has become my favorite way to enjoy them. I find celery root to be one of the more wonderful root vegetables out there- it is just that most people are not familiar with it. It combines the sweet distinctive flavor of celery with an earthiness that comes from the starchy root.
I combine it with sweet yellow onion, a little celery to enhance the flavor and potato to thicken. It is all rounded out with heavy cream (it is the holidays!), which gives the texture and flavor a luxurious edge.
There are definitely some extra steps in the final preparations of the soup, but I find the extra blending and straining of the soup makes quite a difference in the texture and makes it appropriate for a formal dinner.
Celery Root Bisque
2 Tbs butter
1 medium yellow onion, rough chopped
1 ½ cups white wine (whatever you have on hand)
3lbs celery root (once it is peeled, trimmed and rough chopped it will be about 2lbs)
1 ½ lbs of russet potatoes, peeled
2 large stalks of celery
6 cups chicken stock
3 cups water
1 cup cream
Kosher salt and white pepper
Truffle oil and chives for garnish
In a soup pot, melt the butter over medium heat. Add the onion, sprinkle with a little bit of salt and let it sweat and get soft and translucent, cooking them for about 8-10 minutes. Add the wine and let the onions cook for another 5 minutes. Add the celery root, potatoes and celery and stir them to combine with the onions and wine. Add the chicken stock, cover the pot with a lid and turn the heat to low. Simmer the soup on low for 20-30 minutes until the vegetables are very soft and tender.
Remove the soup from the heat and let it sit and cool slightly.
Pour all of the soup into a large heatproof bowl (like a Pyrex). Wash out the pot and set aside.
Two to three cups at a time, add the soup to a blender and puree on high for 15-20 minutes or until the puree is very light and smooth. This is where you should add the water a few tablespoons at a time to make the blending easier. Run each batch of pureed soup through a very fine mesh chinoise strainer, using a small ladle or spatula to press the puree through and into the pot. This will ensure that any of the stringy pulp left from the vegetables doesn’t make it into the soup. When all of the soup is strained into the pot, gently warm the soup over a very low heat.
Add the cream directly to the pot, and whisk gently to completely combine. This is the point when you want to season. You will have to be more generous than usual, as the starch and dairy will really absorb the salt and pepper. I used quite a bit of each, but it is important to add and taste as you can always add more, but you can’t take it away! I then add Nutmeg, a pinch at a time until you can barely detect it- it is a nice compliment to the creaminess of the soup.
Serve the soup hot with a tiny drizzle of truffle oil, and if you desire a snip of fresh chives.