So here it is: the Sandomierz/Lalka/Tybyrczyk family Hamtramck-style pierogi, with one minor edit that I PROMISE you will make you see sauerkraut in a whole new light.
To serve, fry in a pan with butter and eat with sour cream. To serve in a style more characteristic of Krakow than Hamtramck, fry in a pan with butter and onions and eat as is. I do both, but I more often reach for sour cream, because this is comfort food.
The brown sugar is my "secret" for sauerkraut and tomato sauce. It cuts the acidity without adding too much sweetness.
You can also put your favorite pie filling into pierogi wrappers: when I was a kid we just took cans of cherry and blueberry pie filling. I'm planning on updating these to a more "homemade" version, and I suppose I can update later. I also want to try making pierogi ruskie, which I had and loved in Krakow: dry cottage cheese, potatoes, and onions.