Mix the flour and salt in a large mixing bowl. Add the yogurt and oil and work it into the flour. Add most of the water and mix the dough, adding more as needed. You’ll likely need all of it plus another few teaspoons. The dough should come together with no loose flour left over. It will be a little tacky but not sticky. Add more flour, small amounts at a time, until needed. Let rest 15 minutes (while you make the filling).
For the Filling
Peel, cube, and boil the sweet potato. Drain, let cool, and mash it together with the feta cheese. Add pepper. Taste and add salt if needed.
Make the Pierogi
Roll the dough out 1/8 inch thickness. Use a round cookie cutter to cut out circles.
Use a 1 1/2 tablespoon cookie scoop to scoop the filling. Divide each scoop in half and place half on a dough circle.
Fold the dough circle in half around the filling, getting rid of any air. Pinch the dough together, forming a filled half-moon dumpling. (You can dip a finger in water to help seal if needed, but I haven't found it necessary.)
Place on a very lightly floured counter or baking sheet. Repeat for all of the dough and filling.
Cook the Pierogi
Bring a large pot of salted water to a boil.
While the pierogi are boiling, heat a large skillet over medium heat and add the sliced onion. Cook 6-8 minutes, unitl softening and browning. Add the butter and heat together for another 4-5 minutes.
Carefully lower 10-12 pierogi into the water (depending on the size of your pot).
Once they float to the top, boil another 30-60 seconds. Using a cooking spider or slotted spoon, scoop the pierogi out of the water.
To Serve Boiled: Toss the boiled and drained pierogi in the butter and onions, and serve.
To Serve Fried: Push the onions around the pan and add the pierogies. Fry for 3-4 minutes per side, until browned and crispy. Work in 2-3 batches if needed.
Video
Notes
Makes about 40 pierogi. You can serve them boiled or boiled and then pan-fried.The fat and the yogurt help to enrich the dough and make it softer by inhibiting the glutenin and gliadin in the flour from forming strong bonds.Don't crowd the pot when boiling pierogis - this helps prevent them from sticking together.Meal prep! Pierogis freeze well - make extra and freeze them before boiling them for quick dinners!To freeze pierogi, you'll start by flash-freezing.
Place the uncooked pierogis spaced out a bit on a baking sheet. You can dust them with a bit of flour or use parchment paper so they don't stick.
Cover with plastic wrap.
Freeze on the baking sheets for about 2 hours or overnight.
Move the frozen pierogies to a zip-top bag or freezer container for storage. These store well for 3 about 3-4 months. After that, they tend to fall apart during boiling.
To cook frozen pierogis follow the same process as for fresh pierogis. Frozen pierogis will take an extra minute or two longer than fresh pierogis to float. Give them another 30 seconds and then move to a serving bowl with melted butter and cooked onions. Serve.Store leftover cooked pierogis in the fridge in an airtight container for 3 about days. The dough dries out after that.To reheat the pierogies you can microwave them or pan fry until heated through.