Pierogies with Sauteed Onions

We made them a while ago and froze them. The two times we ate them before were served with garlic - butter sauce. It was good, but we wanted to try buttered onions, and it turned out to be good as well! The onions' sweetness came out as they sauteed in the butter, and it was most complimentary to the flavorful pierogies. Yes, they were flavorful! Mark made the dough himself, and filled them with potato-onion filling. Much better than Mrs. T's, if I may say so. No offense.