Ukrainian Vareniki

Ingredients

• 18 ounces potatoes
• 3 cups all-purpose flour
• ¼ cup sour cream
• ½ teaspoon baking soda
• ½ cup water
• ¼ cup butter
• 2 onions, finely diced
• 3½ cups button mushrooms, finely chopped

Method

The dough is the scaffold. Sour cream and baking soda create a tender crumb without yeast — the acid reacts with the alkaline soda to produce carbon dioxide, giving you structure and lift without fermentation time. Start by whisking the sour cream with baking soda in a bowl; watch it foam slightly. In a separate large bowl, combine the flour and 1 teaspoon salt, then pour in the water and fold it through. Add the frothed sour cream mixture and stir until shaggy. Knead for 3–4 minutes until the dough comes together and loses its tackiness — it should feel slightly springy and hold its shape. Wrap and refrigerate for at least 15 minutes; this relaxes the gluten and makes rolling easier.

While the dough rests, prep the filling. Peel and cut the potatoes into 2 cm chunks, then boil in salted water until a knife slides through without resistance — this takes 18–22 minutes depending on size. Drain well and mash whilst still warm, then season generously with salt and pepper. In a heavy-bottomed frying pan, melt the butter over medium heat and add the onions. Cook, stirring occasionally, until deep golden-brown and caramelised — about 10 minutes. The sugars need time to develop colour; this isn't quick work. Add the mushrooms and cook for another 5 minutes until they release their moisture and begin to colour. Fold the onion and mushroom mixture into the warm potato. Taste and adjust seasoning; the filling must be well-seasoned because dumplings are traditionally generous with salt.

Roll the dough into a rope roughly the thickness of your thumb, then cut into roughly 15 mm pieces. On a lightly floured surface, flatten each piece with your palm into a disc about 8 cm across — don't overwork it or it'll toughen. Place a teaspoon of filling slightly off-centre, fold the dough over to create a half-moon, and press the edges to seal. A wet finger helps here. Bring a large pot of salted water to a rolling boil — this is essential for boiling dumplings properly. Working in batches so the water doesn't drop temperature, add the vareniki. They'll sink initially, then float to the surface once the interior is heated through; this takes 2–3 minutes. Once floating, give them another 1–2 minutes to fully cook through. Remove with a slotted spoon and drain briefly. Serve whilst still warm, often finished with a dollop of sour cream and fried onions.