Pierogi

• 1 egg yolk
• 1½ teaspoons canola oil
• 2 cups all-purpose flour, plus more for kneading
• 2 teaspoons salt, plus more for cooking
• 2 tablespoons sour cream or cream cheese
• Potato and Cheese Filling (recipe follows), cooled
• 4 tablespoons (½ stick) unsalted butter

Potato and Cheese Filling

• 2 medium baking potatoes, peeled and cut into 3-inch pieces
• 4 tablespoons (½ stick) unsalted butter
• 4 ounces sharp cheddar cheese, cubed (about 1¼ cups)
• 1 teaspoon salt
• ¼ teaspoon freshly ground black pepper

In a medium bowl, beat together the egg yolk and oil with ½ cup cold water. Set aside.

In a large bowl or the bowl of stand mixer fitted with the dough hook, combine the flour and salt and mix for about 30 seconds. Add the sour cream, 2 tablespoons cold water, and the egg mixture to the flour. Mix until the ingredients are thoroughly combined and the dough is creamy and pliable, about 15 minutes. The dough should not be too sticky; if it is, add a little flour and continue mixing. When the dough is silky and elastic, remove from the bowl and place on a floured surface. Cover and let it sit for 30 minutes.

On a lightly floured surface, roll the dough out to ⅛ inch thick using a rolling pin. Use a 4-inch round cutter to cut out circles of dough.

To make the pierogis, stretch a dough circle slightly with your fingertips and place about 1½ tablespoons of the filling onto the center of the dough. Bring the edges of the circles together to form a half-circle. Using your thumbs, crimp the edges to form a tight seal. (If the dough won’t seal, moisten the edges with cold water.) Place on a lightly floured baking sheet. Repeat with the remaining circles of dough. If making ahead of time, the uncooked pierogi can be frozen on a waxed paper–lined baking sheet. Once frozen, transfer to resealable plastic bags and freeze for up to 3 months.

To cook, bring a large pot of salted water to a low boil. Place the dumplings in the boiling water and cook until they float, 2 to 3 minutes. Remove with a slotted spoon and place in a colander to drain.

In a large, heavy-bottomed skillet, melt 2 tablespoons of the butter. Working in batches, cook the pierogi over medium-high heat until lightly browned, 5 to 7 minutes, adding more butter to the pan as needed. Serve immediately.

To make the potato and cheese filling: Bring a medium pot of water to a steady boil. Add the potatoes and cook until fork-tender, 15 to 20 minutes. Drain and put the hot cooked potatoes in a large bowl with the butter; beat with a hand-held mixer or a potato masher until the potatoes are mashed. Add the cheese and let stand for a few minutes until the cheese melts. Add the salt and pepper and mix until smooth. Set aside to cool completely.