Chef John's Potato and Cheese Pierogi

Prepare the Dough: In a large bowl, whisk together 3 ½ cups flour and 1 teaspoon salt. Make a well in the center. Pour in vegetable oil and 1 cup plus 2 tablespoons warm water. Stir until a shaggy dough forms, pulling away from the bowl's sides. Use a touch of flour to clean the spoon. (5 minutes)

Knead and Rest: Transfer the dough to a lightly floured surface. Knead for 5-7 minutes until smooth and soft, adding a little flour if needed to prevent sticking. Form the dough into a ball, wrap in plastic, and let it rest on the counter for 1 hour, or refrigerate for 3 hours to overnight. (1 hour - overnight)

Sauté the Onions: Melt 0.5 cup butter in a skillet over medium heat. Add diced onion and 0.5 teaspoon salt. Sauté, stirring occasionally, until golden brown and softened. Let cool slightly, then transfer to a bowl and set aside. (8-10 minutes)

Cook the Potatoes: Place quartered potatoes in a large pot and cover with salted water. Bring to a boil, then reduce heat and simmer until tender. Drain well and mash until smooth. Let cool to room temperature. (30 minutes)

Combine the Filling: In a bowl, break up the farmer's cheese with a spoon. Add 1.5 teaspoons salt, pepper, and cayenne. Add 2-3 heaping spoonfuls of the sautéed onions, draining off excess butter. Mix until just combined. Add cooled mashed potatoes and mix thoroughly. (10 minutes)

Assemble the Pierogi: Roll out ¼ of the dough at a time on a floured surface until very thin (about 1/8-inch). Cut out 3 ½-inch circles using a cookie cutter or glass. Save the scraps for re-rolling. (20 minutes)

Fill and Seal: Place about 2 tablespoons of filling in the center of each circle. Moisten your fingertips with water and wet the edges of the dough. Fold the dough over the filling to form a half-moon shape and seal the edges tightly, pressing out any air. Crimp the edges with your fingers or a fork for a decorative touch. (30 minutes)

Boil the Pierogi: Bring a large pot of salted water to a boil. Add pierogi in batches and cook for 2-3 minutes, until they float to the surface. (5 minutes per batch)

Brown in Butter: While the pierogi are boiling, melt 1 tablespoon butter in a nonstick skillet over medium heat. Transfer the boiled pierogi directly into the melted butter and cook until golden brown on both sides. (5 minutes per batch)

Serve: Transfer the browned pierogi to a plate. Top with reserved buttered onions, sour cream, and fresh chives. Serve immediately.