2 cups all-purpose flour
1 egg (optional)
½ tsp salt
Water
Pierogi filling, such as sauerkraut filling or cheese filling
Butter
Sift and measure flour with salt into a large bowl.
Slightly beat egg with fork, and add egg to flour mixture.
Mix in enough water to make a dough that's soft enough to roll out with a rolling pin but not so dry that it spits and cracks.
Roll out dough on a floured bread board to about the thickness of a cracker.
Use a large rimmed glass or a big biscuit cutter to cut rounds approximately 3–4 inches in diameter.
Fill each round with a generous spoonful of filling, and fold dough in half to make a half-moon.
Pinch and seal the edge of the dough with fingers then gently fold and pinch edge to make a ruffled edge with about ¼-inch folds.
Drop each pierogi into a large pot of boiling salted water and boil until they float to the top. Remove each carefully with a slotted spoon.
Fry the pierogi in a skillet with melted butter until golden brown.
Serve warm or cold.