Mustardy Potato Pierogies

• MAKE-AHEAD
• STAFF-FAVORITE
• VEGETARIAN

PIEROGI DOUGH

1. 2 1/2 cups all-purpose flour
2. 1 cup sour cream
3. 1 large egg, beaten
4. 1 large egg yolk, beaten
5. 4 tablespoons unsalted butter, melted
6. 1/2 teaspoon salt

FILLING

1. 3/4 pound medium Yukon Gold potatoes
2. 3 tablespoons sour cream
3. 1 1/2 tablespoons Dijon mustard
4. 4 tablespoons unsalted butter, softened
5. Salt and freshly ground pepper
6. Vegetable oil, for coating
7. 1 tablespoon chopped parsley

1. In a large bowl, mix the flour with the sour cream, egg, egg yolk, butter and salt. On a lightly floured work surface, knead the dough briefly until smooth. Cover the dough with plastic wrap and let rest at room temperature for 15 minutes.
2. In a medium saucepan, cover the potatoes with water and boil until tender, about 12 minutes. Drain the potatoes and peel them as soon as possible. In a bowl, mash the potatoes with the sour cream, mustard and 2 1/2 tablespoons of the butter until smooth. Season with salt and pepper.
3. Bring a large pot of salted water to a boil. On a floured work surface, roll out the pierogi dough 1/8 inch thick. Using a 3 1/2-inch biscuit cutter, stamp out 20 rounds. Brush off any excess flour and moisten the edge of each round with water. Place a level tablespoon of the potato filling on one side of each round, leaving a 1/4-inch border. Fold the dough over the filling to form half-moons and press the edges firmly to seal.
4. Cook the pierogies in the boiling water until tender, about 5 minutes. Drain well and transfer to a large, shallow dish. Add a little vegetable oil and toss to coat lightly.
5. In a large skillet, melt the remaining 1 1/2 tablespoons of butter. Add the pierogies and cook over moderate heat, turning once, until browned, about 3 minutes per side. Transfer the pierogies to a platter. Season with salt and pepper, sprinkle with the parsley and serve.