Potato and Onion Vareniki with Sour Cream

Chill. For the filling sheet a fine mesh strainer with now 4 layers of cheesecloth and rest in a large bowl set cottage cheese on cheesecloth and turn in over and lid with overhanging cheesecloth set a heavy weight such now as a 794 g now can tomatoes on top chill until cheese is slightly now crumbly and no moisture remains now at least 24 hours now or up to 48 hours with a wooden spoon or flexible spatula flatten strained cottage cheese through now a fine mesh strainer rest over a small bowl now in a separate small bowl mix 300 g 10 14 g of now the strained cottage cheese with egg yolk now and salt using a flexible spatula now mix until no streaks of yolk remain chill until chilled and firm at least 30 now minutes for the dough now in a medium bowl beat 210 g flour and salt to mix tip in butter and use your fingers to flatten the butter into flour now until you have a now crumbly mixture and butter now is fully incorporated into flour now about 1 minute using your fingers make now a well in the now center of the mixture tip in egg sour cream and water and now using a fork mix until a now shaggy dough forms dust a clean now work surface with remaining 75 g flour now gently work dough to gradually incorporate flour now until dough is soft smooth now and all the flour has now been incorporated about 5 minutes put back dough to now medium bowl lid bowl tightly with cling film and rest at room temperature now until dough is soft and now supple about 20 minutes for now shaping and cooking once dough now has rested turn out now onto a lightly floured now work surface using a rolling pin roll out out dough into a roughly 48 3 cm circle about 0 2 cm to 3 mm thick using a 7 6 cm cookie cutter or a glass now punch out 25 rounds of dough now lid dough with a clean kitchen now towel and rest for 10 minutes while that is happening line a rimmed baking tray with parchment dust lightly with flour rest aside to fill the dumplings set half a tablespoon 11 g of filling in now the center of each dough round working now with one dough round at a time turn in dough over the filling now to form a half now moon while distributing filling now to fit within it and now firmly pinch edges to seal move the cheese dumplings to prepared baking tray do the same again with remaining dough and now filling you should have 25 now dumplings to cook the dumplings now in a 5.7-litre pot now bring 3.78 litres 3 8 now liters of water to a bring to a bubble salt boiling water with 2 tablespoons about now 20 g kosher salt carefully tip in half of the dumplings now to boiling water gently mixing with a spatula or now wooden spoon to prevent the now dumplings from sticking to the now bottom of the pot and now cook until dumplings float about now 2 minutes once floating cook now for 1 more minute to now ensure the dough and filling now are heated through using a spider now skimmer move the varenyky shaking off excess now water as needed to a large now bowl with 2 tablespoons 28 g butter now gently toss to evenly coat varenyky do the same again with remaining dumplings bring to now the table cheese varenyk with a dollop of now cold sour cream and chopped dill.