1 1/2 tablespoons butter
1 pounds white or cremini mushrooms, wiped clean and thinly sliced
1 celery stalk, chopped
1 yellow onion, peeled and chopped
1 small leek (1/2-inch diameter; white parts only), washed and chopped to measure about 1/2 cup
1 1/2 teaspoons salt, divided
4 cups chicken broth
3/4 cup full-bodied brown ale (such as Deschutes Buzzsaw or Rogue Hazelnut Brown Nectar)
2 medium-sized Yukon Gold or other yellow-fleshed potato, peeled and chopped to measure scant 2 cups
1/2 tablespoon apple-cider vinegar
1/2 cup finely ground, roasted and skinned hazelnuts
1 teaspoon freshly ground black pepper
1/4 cup sour cream
1 tablespoon heavy cream
About 1/2 tablespoon dried crumbled sage (or fresh sage leaves), for garnish
1/3 cup coarsely chopped, roasted and skinned hazelnuts, for garnish
In a heavy, 4-quart pot, melt the butter over medium-low heat. Add the mushrooms and saute until moisture they release has cooked off and mushrooms begin to brown. Add the celery, onion, leek and 1 teaspoon of the salt and saute for 5 minutes. Add the chicken broth, ale, potatoes and vinegar and cook until potatoes are soft, about 20 minutes.
Add the finely ground hazelnuts. Puree soup in batches in a blender or food processor (or directly in pot with a hand-held blender). Soup may be made several days ahead and refrigerated.
Thin the sour cream by whisking in the heavy cream. To serve, ladle soup into bowls and garnish each with a swirl of sour cream, a pinch of sage (or a whole sage leaf) and a sprinkling of coarsely chopped hazelnuts. To make a pretty design with sour cream, place dollop in center of each serving, then draw a skewer through it at several points to create desired pattern before adding other garnishes.
Makes 4 servings.