Pierogi Ruskie (Potato and Cheese Pierogi)

1. Dough Preparation

Begin by whisking together 2 cups of all-purpose flour with a teaspoon of kosher salt in a large bowl. In a small saucepan, gently heat 3 tablespoons of unsalted butter with an equal amount of water just until the butter melts. Pour this warm mixture into the flour and stir to combine. Add a beaten large egg to the mixture, and start to knead it on a lightly floured surface until it becomes smooth and elastic, about 8 minutes. Let it rest for 30 minutes covered with a damp towel.

2. Filling Creation

Boil 1/2 pound of potatoes until tender, approximately 15 minutes. While the potatoes cook, melt another 3 tablespoons of unsalted butter in a skillet and cook 3 finely chopped medium yellow onions until caramelized. After draining the potatoes, mash them and season with salt and pepper to taste. Combine the mashed potatoes with the caramelized onions and 1/2 cup of quark cheese. Allow this mixture to cool before assembling the pierogi.

3. Rolling and Cutting the Dough

On a lightly floured surface, roll out the dough until it's about 1/8-inch thick. Use a 3-inch cookie cutter or the rim of a glass to cut out dough disks. Place them on a baking sheet to prevent sticking.

4. Assembling the Pierogi

Place a spoonful of the potato and cheese filling in the center of each dough disk. Fold the dough over to create a half-moon shape, pressing the edges firmly to seal. If the dough resists sealing, dab a bit of water along the edge to help it adhere.

5. Cooking the Pierogi

Bring a large pot of salted water to a rolling boil and cook the pierogi in batches. They're done when they float to the surface, about 5 minutes. Use a slotted spoon to transfer them to a colander to drain.

6. Optional Pan-frying

For an extra layer of texture and flavor, pan-fry the boiled pierogi in some butter until each side turns a crispy golden brown, usually about 1-2 minutes per side.

7. Serving

Serve your pierogi hot, topped with a dollop of sour cream, a sprinkle of fresh parsley or dill, and a spoonful of the caramelized onions.