Potato and Portobello Mushroom Gratin - water

Method

• 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 saute 4 minutes.
• Stir in garlic and reserved porcini and saute until mushrooms are tender, about 10 minutes.
• Season with salt and pepper.
• Remove from heat.
• Preheat oven to 375F.
• 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 350F oven about 20 minutes.)
• *Dried porcini mushrooms are available at Italian markets, specialty foods stores and many supermarkets.