Sauerkraut Pierogi

To make the sauerkraut filling, heat the oil over medium heat. Add the onion and cook until tender. Add the sauerkraut and carrots. Cook, stirring often, for 10 to 15 mins or until the sauerkraut is tender. Remove from heat and stir in the salt, pepper, and sour cream. If the mixture doesn’t hold its shape when squeezed together, add more sour cream. Let this filling cool completely.
To make the dough, combine eggs, sour cream, oil and salt. Add the flour and knead by hand or in a stand mixer until the dough is smooth. Wrap with plastic and let rest at least 10 mins before rolling. Then, on a lightly floured surface, roll out to 1/8-inch thickness. Using a 3-inch round cutter, cut into circles. Gather the scraps, cover with plastic wrap and set aside. Portion the sauerkraut filling onto all the dough circles before folding into half-moon shapes. Press the edges together with your fingers (or a fork). Roll, cut, and fill the reserved scraps of dough.
Bring a pot of salted water to a boil. Reduce to a simmer and drop 12 pierogi at a time into the water. Stir once so they don’t stick to the bottom. When they rise to the surface, cook 3 mins or until the dough is done. Place them on a platter smeared with butter.