Potato and cheese pierogi are sauteed in butter and caramelized onions for a delicious and indulgent dish. Served as an appetizer, main course, side dish or dessert, pierogies are the ultimate form of comfort food.
Whisk together warm water, milk, egg and salt. Stir in flour until combined. Cover with a kitchen towel and let sit for 15 minutes.
Add 1/2 teaspoon of vegetable oil and knead until dough is smooth and elastic. Dough will be slightly sticky at first. Knead for 5-10 minutes until dough is stretchy.
Cover the bowl for 45 minutes. Dough will not rise, this just allows the gluten to relax so the dough can be shaped and stretched easier.
While the dough is resting, make the filling. Mix together mashed potatoes, cheddar cheese, sour cream, and 1/2 teaspoon of salt. The filling should be able to stick together.
Sprinkle flour on the counter and roll out the dough until it is 1/8 inch thick. Use a ramekin or cookie cutter that is 3-4 inches wide. Cut out dough into circles. Place 1 tablespoon of filling inside circle. Wet the edge with some water, fold the circle in half, and press edges together with a fork. Continue the process until all of the dough has been used up.
Boil a pot of water and add 1 tablespoon of salt. Place 5-6 pierogies in the boiling water and boil until they float. Once floating, allow water to return to a boil and cook an additional 4-5 minutes.
In a large skillet, melt the butter over medium heat. Add shallots and cook until golden. Add drained piergoi and fry until browned and crisped.