After more than a month of real drought, we had a prolonged, soaking rain on Wednesday. Because of the drought our October was unusually warm and sunny—beautiful really—but I have missed the rain. Wednesday began grey and cool and then turned windy, cold and blustery by evening. The rain continued to fall into the night...it was wonderful. And just as with our one cool day last week, it was a perfect day for soup. But this time, instead of a hearty, chunky vegetable and bean based soup, I made a velvety purée of celery root and apple.
Celery root and apples are natural flavor partners—in both their raw and cooked form. Recipes for a soup made from these two are easy to find. Typically these soups use Granny Smith apples, but I have seen some recipes that use sweeter apples (Fuji and Ginger gold, for example). You may use any apple that pleases you, but I love the tartness of the Granny Smiths in this soup. Most recipes use onions for the flavor base, but I have chosen to use leeks. I like the richness they add, but as with the choice of apples, you should feel free to use onion instead.
Most puréed soups—especially those made with vegetables that have a relatively small amount of natural starch (cauliflower, carrots, celery root, turnips, etc.)—need to have a thickener of some kind. A thickener will add body and will also prevent the vegetables from separating into their fibrous and liquid components. A potato is frequently the starchy addition of choice. It would not be a bad choice for this soup—potatoes and celery root are wonderful together. But when I made my soup, I was more interested in the flavors of the celery root and apple. I thought the addition of the potato would mute these flavors too much.
Another, less obtrusive way to add starch to a puréed soup is to add some rice. To use rice, simply add it a minute or two before adding the liquid. Allow it to cook briefly in the fat with the vegetables. After the liquid has been added, make sure that the soup cooks for at least 20 minutes so that the rice will be fully cooked before the soup is puréed. Soups thickened with rice have a lovely, velvety texture.
Puréed soups are always more interesting when they are finished with a garnish of some kind—and there are lots of possible garnishes for this soup. A few sautéed mushrooms floated in each bowl...a spoonful of cooked wild rice...a few crumbles of blue cheese along with some minced walnuts... At epicurious, I found a particularly appealing garnish: a scattering of crispy, salty pancetta. A final drizzle of a fragrant nut oil (walnut or hazelnut), truffle oil or a flavorful extra virgin olive oil will enhance any garnish you choose.
When served in small (1 cup or less) portions, puréed soups are an elegant first course. But it would be limiting to assume that they are only for the formal setting of the multi-course meal. In larger portions this soup is a filling and soothing entrée. The addition of some biscuits, a crusty artisanal loaf of bread or even a grilled cheese sandwich, make it a meal...and it was absolutely perfect on our recent cold and rainy evening.
Celery Root & Apple Soup
4 T. unsalted butter
2 large leeks, white and pale green parts only, halved, thinly sliced and well rinsed (about 2 1/2 to 3 cups)
2 medium celery root (about 1 lb. each), peeled, quartered and thinly sliced (about 6 cups)
2 Granny Smith Apples (about 7 oz. each), peeled, quartered, cored and thinly sliced (2 1/2 to 3 cups)
2 cloves garlic, minced
2 T. white rice
1/2 c. dry white wine
5 to 6 c. Chicken stock or low-salt canned broth
1/2 c. heavy cream
Salt & Pepper
2 to 3 oz. minced pancetta, cooked until crisp in a bit of butter
Minced Italian Flat leaf parsley
Extra Virgin olive oil
In a large stockpot, melt the butter over medium heat. Add the leeks, celery root, apples and garlic along with a generous pinch of salt.
Cook, stirring occasionally, until softened—about 5 to 10 minutes.
Add the rice and cook for a minute or two. Add the white wine, bring to a simmer and reduce to a glaze. Add enough stock so that the vegetables are just covered and moving freely. Bring to a simmer. Season with salt. Cover and cook over low heat until the celery root and apple are very soft—about 30 minutes.
Purée the soup in batches (the blender should only be filled half way when puréeing hot liquids), adding more stock (or water, if you prefer) if the soup is too thick. Pass the puréed soup through a fine meshed sieve, pressing on the solids to extract as much soup as possible. Return the soup to the pot and add the cream. Heat through. Taste and correct the seasoning. Serve immediately, garnished with the pancetta, herbs and a drizzle of olive oil.
Makes about 2 quarts soup.