dough:

1 pound all purpose flour
lukewarm water
1 egg, lightly beaten
a pinch of salt

filling:
2 pounds scrubbed and peeled baking potatoes
8 ounces very well-drained cottage cheese or ricotta
1 small white onion, diced fine
1 tablespoon butter
1/2 teaspoon coarsely ground pepper
salt

1. Boil the potatoes in lightly salted water. Drain and refrigerate. Before cooking, mash potatoes roughly.

2. Sauté the onion in butter until golden and translucent. Crumble the cheese and combine it with the potatoes and onions. Season with salt and pepper to taste. The mixture should be lumpy for proper texture.

3. Mound the flour onto a clean counter or board and make a small indentation in middle. Pour the egg into the indentation. Add the salt and a little bit of the lukewarm water. Knead until smooth, adding small amounts of water and flour as necessary. Dough should be soft and rolled out thin, similar to fresh pasta.

4. Using a glass or biscuit cutter, cut out circles from the dough and keep them covered until used. Scoop about a half tablespoon of filling in your hand, squeeze any remaining liquid from it, and place it on one side of each dough circle. Fold the dough over the filling (you get a half circle) and seal by pressing with the tines of a fork or your thumb, making sure none of the filling comes through the edges. The pierogi should appear slightly overstuffed and plump. Practice on a couple to get the amount right.

5. In small batches, drop the pierogi into boiling salty water, stir carefully to prevent them sticking together, and cover loosely. When they float to the top, uncover the pot, lower the flame, and boil an additional 2-3 minutes. Remove with a slotted spoon, brush with butter to keep from sticking and keep covered to prevent them from drying out. Serve with bacon and sour cream on the side.

Leftovers can be boiled again for a few minutes to warm them up.