To make paste, mix sifted flour with and egg, add cool water with dissolved salt and sugar. Knead stiff dough and let it sit for 30 minutes to develop gluten.
To make filling, shred cabbage finely, add boiling water, let stay for 5-6 minutes and drain the water. Pat the cabbage dry, add salt, eggs and butter and stir well.
Cut the paste into several pieces, roll them into braids 3/5-4/5 inch (1.5-2 cm) thick and cut the braids into small chunks, press them slightly over the cuts and roll out very thin circles. Put the prepared filling in the middle of each circle and pinch or crimp the edges. Shape the wraps like half moon. The flat circles could be made the other way: roll the paste in thin layer first and cut it with round dough cutter or with a glass.
Put the prepared wraps on boards, dusted with flour and cool.
Before serving plunge the wraps in salted boiling water using 4 quarts (4 liters) of water for 2 pounds (1 kg) of wraps. Bring to a boil and boil for 5-7 minutes. Take the cooked wraps off the water with a skimmer and turn on a serving platter, relish with butter.
Cover the wraps with sour cream just when serving.