POTATO AND PORTOBELLO MUSHROOM GRATIN

Steps:

• Combine 1 1/2 cups hot water and porcini in small bowl. Let stand until mushrooms soften, about 30 minutes. Drain, reserving 2/3 cup soaking liquid. Chop porcini; set aside. Remove and chop stems from portobellos; place in large bowl. Using small spoon, scrape away dark gills from portobellos and discard. Cut portobello caps into 1/2-inch pieces; add to bowl.
• Heat 3 tablespoons olive oil in heavy large skillet over medium-high heat. Add chopped portobello stems and caps and sauté 4 minutes. Stir in garlic and reserved porcini and sauté until mushrooms are tender, about 10 minutes. Season with salt and pepper. Remove from heat.
• Preheat oven to 375°F. Coat each of two 13x9x2-inch glass baking dishes with 1 tablespoon oil. Combine remaining 7 tablespoons oil, potatoes, parsley, thyme, rosemary, salt and pepper in large bowl; toss to coat. Layer 1/6 of potato mixture in each prepared dish (there will not be enough to overlap slices). Top potatoes in each with 1/4 of mushroom mixture. Repeat layering. Top with remaining potatoes. Pour 1/3 cup reserved porcini soaking liquid over potatoes in each dish. Cover dishes with foil.
• Bake gratins 45 minutes. Uncover and bake until tops are brown and potatoes are tender, about 40 minutes longer. (Can be prepared 2 hours ahead. Let stand at room temperature. Cover with foil and rewarm in 350°F oven about 20 minutes.)
• *Dried porcini mushrooms are available at Italian markets, specialty foods stores and many supermarkets.