(c) 2008 Barbara Rolek licensed to About.com, Inc.
Pierogi can be boiled fresh or frozen. Bring a deep pot of salted water to a rolling boil. Reduce to a simmer and drop 12 pierogi at a time into water. Stir once so they don't stick to the bottom. When they rise to the surface, cook 3 minutes or until dough is done to your liking (based on thickness of dough).
Remove with a slotted spoon to a platter that has been smeared with butter. Pierogi will stick together if drained in a colander, even if the colander has been coated with cooking spray.
Repeat until all pierogi are cooked. Serve with melted butter, confectioners' sugar (for sweet fillings) and sour cream, if desired. Or sauté in melted butter until golden (see the next step).