1-1/2 Tbs. butter or 3 Tbs. vegetable oil, for sautéing (optional)
melted butter, sautéed pancetta, sautéed onions or sour cream and snipped chives for serving (optional)
To make the filling:
- Put the potatoes in a pot with just enough cold salted water to cover them and boil until soft, 15 to 20 minutes.
- Meanwhile, melt the butter with the oil in a large sauté pan over medium heat. Add the onion and cook until the onions are translucent, about 2 minutes. Lower the heat and continue cooking until the onion is nicely browned and caramelized, about 20 minutes. Season with salt and pepper. You may need to add 1 tablespoon or more of additional butter, as the mixture will absorb quite a bit of fat. Set aside to cool.
- When the potatoes are tender, drain them in a colander and press lightly with a dry kitchen towel to dry them thoroughly. Return the potatoes to their hot pot and shake them dry.
- Remove the pot from the heat; add the cooled onion mixture and the cheese. Mash the ingredients until they’re well blended and there are no more potato lumps; you may want to use a stiff whisk. Season with salt and pepper. Set aside to cool while you roll out the pierogi dough.
- Put the flour in a large bowl. Add the butter and using your fingers, work it into the flour until the mixture has the texture of coarse meal. Add 1 3/4 cups of the warm water and stir with your fingers until the mixture begins to come together. If the mixture is dry, you can add up to 1/4 cup more warm water, 1 tablespoon at a time until the dough forms a shaggy yet cohesive mass.
- Turn the dough out onto a well-floured work surface and gently knead it until just soft and elastic; the dough will not be completely smooth, but it should be easy to shape, with a Play-Doh-like consistency.
To shape and fill the pierogi
- Fill a large pot with 5 qt. water and bring it to a boil over high heat. Meanwhile, using lightly floured hands, pinch of one tablespoon portions of the dough and roll them into balls about 1-1/2 inches in diameter. You should end up with 36 to 40 balls. With a small rolling pin or dowel, gently roll out each ball into a 3 to 3-1/2-inch round about 1/8 inch thick on a well-floured surface. Keep the dough balls and disks covered as you work so they won’t dry out.
- Hold a round of dough flat in your palm, dust off the excess flour, and spoon a generous tablespoon of the filling onto the center of the dough. Fold the round in half to enclose the filling. Seal the pierogi by pulling the edges away from the filling and pinching them together. To ensure a proper seal, pinch the edge shut once more, working from one end to the other. Set the filled pierogi on a floured work surface or baking sheet and cover with a dry towel or plastic wrap until all are filled. Repeat with remaining dough and filling.
To cook the pierogi:
- When the pot of water is boiling, drop the pierogi in batches into the boiling water, stirring occasionally. When they float to the top, cook for another 2 to 4 minutes; bite into one to check that there’s no chalky line. Remove cooked pierogi from the water with a spider or slotted spoon and put them in a bowl. If you like, serve them immediately with melted butter.
- To sauté the pierogi, heat the butter or vegetable oil in a sauté pan over medium-high heat. Without crowding the pan, add the boiled, drained pierogi and cook until golden brown and puffy on both sides. Season with a little salt and pepper, and serve with sour cream and chives, if desired.