Yield: 6 to 8 servings
3 large russet potatoes, quartered
1. In a large stockpot, place potatoes. Cover with cold water, and bring water to a boil. Cook potatoes until tender, 10 to 12 minutes. Remove from heat, drain, and let cool. Refrigerate for at least 4 hours.
3 tablespoons peanut oil
1 medium red onion, thinly sliced
1 teaspoon kosher salt, divided
½ teaspoon ground black pepper, divided
2 tablespoons butter, softened and divided
Garnish: fresh thyme
2. Cut potatoes into ½-inch cubes.
3. In a 12-inch cast-iron skillet, heat peanut oil over medium-high heat until it just begins to smoke. Add onion, and cook, stirring often, until tender, about 5 minutes. Remove and set aside.
4. Add half of potatoes to skillet, spreading to cover entire surface of pan. Cook potatoes in 2 batches, being careful not to overcrowd pan. Sprinkle potatoes with ½ teaspoon salt and ¼ teaspoon pepper. Cook, without stirring, until potatoes are golden brown on the bottom, 8 to 10 minutes.
5. Add 1 tablespoon butter to pan. Carefully flip potatoes, and cook until bottoms are golden brown. Set aside. Repeat with remaining potatoes, salt, pepper, and butter.
6. Return cooked potatoes and reserved onion to pan. Stir to combine and heat through. Garnish with thyme, if desired. Serve immediately.