Crispy Potato, Onion, and Mushroom Rösti2013-04-24
Potatoes, onions, and mushrooms are crispy and golden brown on the outside, creamy and tender in the middle.
Note: For best results, cut potatoes into 1/16th-inch matchsticks by hand or on a mandoline. If you don’t have one, the large shredding disk of a food processor or large holes of a box grater will do fine.
3 medium potatoes (about 1 pound) rinsed and cut into 1/16th-inch matchsticks or grated (see note above)
1 medium onion, finely sliced (about 1 cup)
4 ounces button mushrroms, finely sliced
2 cloves, grated on a grater
1 teaspoon picked fresh thyme leaves
Kosher salt and freshly ground black pepper
Spread potatoes on a large microwave-safe plate and microwave on high heat until hot all the way through and softened but still slightly crunchy, about 5 minutes.
Meanwhile, heat 1 tablespoon oil in a 10-inch well seasoned cast iron or nonstick skillet over medium-high heat until shimmering. Add onions and mushrooms and cook, stirring and tossing occasionally, until softened and starting to brown, about 8 minutes. Add garlic and thyme and cook, stirring frequently, until fragrant, about 30 seconds. Season to taste with salt and pepper. Transfer to a small bowl and wipe out skillet.
Heat 2 tablespoons oil in skillet over medum heat until shimmering. Add half of potatoes and press into bottom of the pan with a rubber spatula. Season with salt and pepper. Spread onion/mushroom mixture evenly over the potatoes and top with remaining potatoes. Press down into an even disk shape using a rubber spatula. Season top with salt and pepper.
Cook, swirling and shaking pan occasionally until deep golden brown and crisp on the first side, about 7 minutes. Carefully slide rösti to a large plate. Set another plate on top of it upside down, grip the edges, and invert the whole thing so the rösti is now cooked-side-up. Heat remaining two tablespoons oil in the skillet and slide rösti back in. Continue cooking, swirling and shaking pan occasionally until deep golden brown and crisp on the second side, about 7 minutes longer. Slide rösti to a cutting board.