Mix the flour and salt, and add the water to make a dough that doesn't stick to your fingers. Knead well and cover with a damp cloth for 10 minutes.

Combine the potatoes and cottage cheese to make the filling.

Roll the dough out to 1/8" thick. Cut in squares or circles and fill with the filling. Pinch closed.

Bring a large pot of water to a boil. Salt generously. Working in batches, add 10 or so pierogi to the boiling water and stir to make sure they don't stick to the bottom. Cook the pierogi until all the pierogi have floated to the surface and then 1 to 2 minutes longer to make sure the filling gets hot — 8 to 10 minutes total.

Melt the butter in a large skillet over medium heat. Add the onions and cook until the onions are translucent, very soft, and beginning to brown, 8 to 10 minutes. Push the onions to the edges of the pan where they will stay warm and continue to caramelize.

Transfer the pierogi to the pan with the onions. Turn the heat to medium-high. Cook the pierogi without moving until they are golden and crispy on the bottoms, 2 to 3 minutes.

Once all the pierogi have been boiled and crisped, scrape the onions over the pierogi and gently stir to coat the pierogi with butter and onions. Serve immediately while hot.

Almost anything goes. Fried onions and sour cream are traditional but you can also serve with mushroom gravy, etc.

Homemade pierogies actually cook better when they're frozen! I roll/shape them and then lay them flat on a cookie sheet and freeze quickly.

Definitely do not boil and then freeze.

As soon as they're frozen, I toss them into zip lock bags. They never stick and I never "lose" any, a problem that occurs when they open up in the boiling stage.

Even though you can cook directly from the freezer I let mine thaw just a little. Then I boil and fry up in butter with onions after that.