1. Put the dried mushrooms in a heatproof bowl and cover with 2 cups boiling water. Let stand until mushrooms are softened, for about 20 minutes. Strain mushrooms in a strainer lined with a double thickness of paper towels, reserving the soaking liquid. Press down on the mushrooms and the paper towels to release any juices collected in them; it should yield about 1 1/2 cups. If not, add enough water to equal this amount. Coarsely chop the mushrooms. 

2. Heat 2 tablespoons of the butter and the olive oil in a large, heavy pot set over medium heat. Add the sliced white mushrooms, shiitakes and salt, and cook, stirring, for 3 minutes.

3. Add the shallots and continue to cook, stirring, until mushrooms and shallots are softened and browned, for about 5 more minutes. Add garlic, thyme, and chopped porcinis; stir and cook 1 minute more. (The soup can be prepared 1 day ahead to this point. Cool, cover, and refrigerate mushroom mixture and porcini soaking liquid separately. Reheat mushrooms over medium heat before continuing.)

4. Add 3 cups stock, wine, reserved porcini soaking liquid, and wild rice to the pot. Simmer, covered, until wild rice is tender, but still slightly crunchy to bite, for 40 to 50 minutes.

5. Taste soup and season with more salt, as needed, plus several grinds of pepper. To serve, ladle soup into 4 bowls and sprinkle each serving with chopped parsley. Serve immediately.

Betty Rosbottom, Sunday Soup, Chronicle Books (2008).