01 -
Combine flour and salt in a large mixing bowl. Heat water with butter until very hot but not boiling, then pour into the flour mixture, stirring with a wooden spoon until it begins to form a dough.
02 -
Knead the dough by hand or with a mixer fitted with a dough hook for about 5 minutes until smooth, soft, and elastic. Adjust moisture with additional water or flour as needed. Wrap in plastic and let rest for 30 minutes.
03 -
Boil peeled potatoes in salted water until tender, then drain and mash thoroughly. Sauté diced onions in frying oil over medium-low heat for approximately 10 minutes until translucent. Combine mashed potatoes, cheese, and sautéed onions in a large bowl, seasoning generously with salt and pepper.
04 -
Optionally, form the potato and cheese mixture into small 0.7-ounce balls or use a teaspoon to portion filling for each dumpling. Chill filing in refrigerator for 30 minutes if necessary for firmness.
05 -
Divide dough into four portions. On a lightly floured surface, roll out one portion to a thin sheet about 1/16 inch thick. Cut circles with a 2 3/4 inch diameter cutter. Gather scraps and re-roll as needed.
06 -
Place a portion of filling onto each dough circle. Fold dough over to form a half-moon and firmly pinch edges to seal. Arrange dumplings on a floured surface and cover with a cloth to prevent drying.
07 -
Bring a large pot of salted water to a boil. Cook dumplings in batches to prevent sticking. Once they float to the surface, continue boiling for 1–2 minutes. Remove with a slotted spoon and drain well.
08 -
Transfer cooked pierogi to a plate or tray and toss lightly with melted butter to prevent sticking. Serve immediately.