In a large bowl, combine flour and salt with a fork or whisk. Add sour cream, and butter, and work the dough. Stir to combine as best as you can and then knead with your hands for a minute. Transfer the dough to a lightly floured surface and continue to work it with your hands for a few minutes. The dough should come together and but still be a little shaggy.
Wrap the dough in a clean kitchen towel or plastic wrap and refrigerate for 30 minutes or up to 48 hours.
While the dough is resting, let’s make the filling. Peel the potatoes and cut them into 1-inch cubes. Add to a medium saucepan, cover with two inches of water and add ½ tbs salt. Bring the water to a boil over high heat then lower to a low boil and boil until potatoes are tender. At about 15 minutes start checking them with a butter knife.
Once the potatoes are tender, turn off the heat, drain them and add them back to the pot. Add oat milk and butter and mash until thoroughly mashed. Add nutritional yeast, miso, vinegar, cheddar, salt & pepper, mash to combine again and set aside.
Bring a large pot of salted water to boil while you make the dumplings.
Once the dough has been resting for long enough, pull it from the fridge and cut in half. Keep one half under a kitchen towel or rewrap in plastic wrap and roll the other half out until it’s about 1/8” thick. Use a 3” round cookie cutter or the 3″ top of a drinking glass to cut out circles of dough.
Keeping a small bowl or cup of water nearby, take a dough circle and add a heaping tsp of the mashed potato filling. Dip the tip of your finger in the water and run it along the edge of half of the circle. Fold the circle in half over the filling and pinch the ends together with your fingers to seal. Repeat until the dumplings are made and then repeat the whole process with the other half of the dough you reserved.
If you’d like to freeze the pierogi for another day, this is the time. Just use them within a month.
Otherwise, time to boil! Depending on the width of your pot opening, drop about 7-10 pierogi in at a time. Don’t overload the pot otherwise they will stick.
The pierogi will float in a couple of minutes and then cook for 1-2 minutes after that till they look nice and plump. Using a slotted spoon, transfer them to a plate and repeat until all of them are cooked.
Don’t overlap the dumplings because they will stick to each other, you’ll probably need a few plates or you can use a baking sheet.
[If you’d like caramelized onion on your pierogi, which I highly recommend, go ahead and make that now]
Once all of the pierogi are boiled, heat a large skillet over medium-high heat. Add 1 tbs butter and once melted, add 1/3 of the pierogi. Cook until browned, about 1-2 minutes, then flip and cook on the other side. Repeat until all pierogi are seared on the outside. Serve with desired toppings!