Nonstick vegetable oil spray
2 1/2 pounds small red-skinned potatoes, unpeeled, cut into 1 1/2-inch wedges
5 tablespoons extra-virgin olive oil
1 pound crimini or white button mushrooms, halved if large
1/2 ounce dried porcini mushrooms,* ground to powder in blender
3 tablespoons chopped fresh Italian parsley
Preheat oven to 425°F. Spray large rimmed baking sheet with nonstick spray. Combine potatoes and 2 tablespoons oil in large bowl; toss to coat. Transfer potatoes to prepared sheet. Roast until tender and brown, stirring occasionally, about 45 minutes.
Meanwhile, heat 2 tablespoons oil in heavy large skillet over medium-high heat. Add crimini mushrooms; sauté until brown and tender, about 12 minutes. (Potatoes and mushrooms can be made 2 hours ahead. Let stand separately at room temperature.)
Add potatoes and remaining 1 tablespoon oil to skillet with mushrooms. Sauté over medium-high heat until potatoes are crisp and heated through, about 6 minutes. Season to taste with salt and pepper. Sprinkle with porcini mushroom powder; toss to coat. Transfer to bowl, sprinkle with parsley, and serve.
*Dried porcini mushrooms are available at Italian markets, specialty foods stores, and many supermarkets.