From America's Test Kitchen Season 2: Three Pureed Vegetable Soups
Mushroom soups have great potential, but they often disappoint with their lackluster taste and less-than-stellar texture. We knew this pureed soup could be richly textured, neither too thick nor too thin, and showcase the deep, earthy flavor of mushrooms. We chose to use readily available white mushrooms, which are often underestimated; fresh wild mushrooms were shelved because they can be expensive and difficult to find. To bring out the most flavor from the mushrooms, we had to slice them by hand (processing made for uneven and bruised pieces) and then sweat them in a covered pot with butter and shallots; roasted mushrooms were nixed because the juices released during roasting had browned on the pan and were lost, making for flavorless soup. Chicken broth proved a better addition than water for the liquid base, and dried porcini mushrooms amplified the mushroom flavor. After pureeing the soup, we added cream and a splash of Madeira for body. Our creamy mushroom soup was now texturally light and full of deep, rich flavor.
Makes 8 cups, serving 6 to 8
To make sure that the soup has a fine, velvety texture, puree it hot off the stove, but do not fill the blender jar more than halfway, as the hot liquid may cause the lid to pop off the jar.