This brunch dish is crispy and golden brown on the outside, creamy and tender in the middle, flavored with sautéed onions and mushrooms.
- 3 medium russet potatoes (about 1 pound; 450g), rinsed and cut into 1/16-inch matchsticks or grated (see note)
- 5 tablespoons (75ml) olive oil
- 1 medium onion, finely sliced (about 1 cup)
- 4 ounces (115g) button mushrooms, finely sliced
- 2 cloves garlic, grated on a Microplane 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 (15ml) oil in a 10-inch well-seasoned cast iron or nonstick skillet over medium-high heat until shimmering. Add onion 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 (30ml) oil in skillet over medium heat until shimmering. Add half of potatoes and press into bottom of pan with a rubber spatula. Season with salt and pepper. Spread onion/mushroom mixture evenly over 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 onto 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 2 tablespoons (30ml) oil in 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 onto a cutting board. Serve immediately with a side of vegan aioli.
For best results, cut potatoes into 1/16-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.