Lyonnaise Potatoes

In a large pot, cover potatoes with 1 inch cold water (about 2 quarts; 1.9L). Add salt and vinegar. Bring to a boil over high heat, then reduce heat to maintain a simmer. Cook until potatoes are barely tender, offering some resistance when poked with a paring knife, about 4 minutes. Drain potatoes; set aside. Vicky Wasik Meanwhile, in a 12-inch cast iron skillet, nonstick skillet, or stainless-steel sauté pan or skillet, heat 1 tablespoon (15g) clarified butter over medium-high heat until shimmering. Add onion, season lightly with salt, and cook, stirring occasionally, until lightly browned and softened, about 10 minutes. Add 1 tablespoon (15ml) water and scrape up browned bits on bottom of skillet. Transfer onions to a medium heatproof bowl and set aside. Vicky Wasik Add 2 tablespoons (30g) clarified butter to now-empty skillet and heat over medium-high heat until shimmering. Add half of the drained potatoes in a single even layer and cook, without moving, until golden brown on bottom, about 3 minutes, adjusting heat as needed if at risk of scorching. Using an offset or thin metal spatula, flip potatoes and continue to cook until completely tender, offering little to no resistance when poked with a paring knife, and golden brown on second side, about 3 minutes. Transfer potatoes to bowl with onions and set aside. Vicky Wasik Add remaining 2 tablespoons (30g) clarified butter to now-empty skillet and repeat with remaining potatoes. Return reserved potatoes and onions to skillet, toss to combine, and cook until heated through, about 1 minute. Season with salt and pepper to taste. Vicky Wasik Transfer pommes lyonnaise to a serving bowl, sprinkle with parsley, and serve immediately. Vicky Wasik