Vareniki (Pierogi) with Potatoes and Mushrooms

Prepare the Potato Filling: Place the potatoes in a large pot and cover with cold, salted water. Bring to a boil over high heat, then reduce the heat to medium-low and simmer until the potatoes are fork-tender, about 25 minutes. Drain the potatoes thoroughly and mash them until smooth. Season generously with salt and freshly ground black pepper. Set aside to cool slightly.

Make the Dough: While the potatoes are cooking, combine the flour and 1 teaspoon of salt in a large mixing bowl. In a separate small bowl, stir together the sour cream and baking soda. Add the cold water to the flour mixture, followed by the sour cream mixture. Mix until a shaggy dough forms. Turn the dough out onto a lightly floured surface and knead for 5-7 minutes, or until smooth and elastic. Wrap the dough tightly in plastic wrap and refrigerate for at least 15 minutes, or up to 1 hour. (15 mins)

Sauté the Mushrooms and Onions: Melt the butter in a large skillet over medium heat. Add the diced onions and cook, stirring occasionally, until softened and lightly browned, about 8-10 minutes. Add the chopped mushrooms to the skillet and cook, stirring occasionally, until they release their moisture and are browned, about 8-10 minutes. Season with salt and pepper to taste.

Combine Filling Ingredients: Add the sautéed mushroom and onion mixture to the mashed potatoes. Mix well to combine all of the filling ingredients.

Assemble the Vareniki: Divide the dough into 4 equal portions. On a lightly floured surface, roll out one portion of the dough into a thin circle, about 1/8 inch thick. Use a cookie cutter or a glass to cut out circles of dough, about 2-3 inches in diameter. Place a teaspoon of the potato and mushroom filling in the center of each dough circle. Fold the dough over to form a half-moon shape, and firmly press the edges to seal. Crimp the edges with a fork for a decorative touch and to ensure a tight seal. Repeat with the remaining dough and filling.

Cook the Vareniki: Bring a large pot of salted water to a gentle boil. Carefully add the vareniki to the boiling water in batches, being careful not to overcrowd the pot. Cook until the vareniki float to the surface and are cooked through, about 3-5 minutes after they rise. Remove the cooked vareniki with a slotted spoon and place them in a colander to drain.

Serve: Serve the vareniki hot, garnished with a dollop of sour cream, chopped fresh herbs (such as dill or parsley), and a drizzle of melted butter, if desired.