Put raw bacon in a pan and cook it down until the fat is rendered out of it.
Next add the cabbage.One medium head shredded up should be sufficient. Also add half of a sliced onion and let that simmer until it's all wilted down.
Depending on how high the heat you're using and how frequently you stir it, it should take about 20 minutes or so.
Season with salt and pepper to taste.
Once that is complete, put in the kielbasa.
As that is cooking, have salted water boiling on the stove to cook the pierogi in it while this is finished up. Cook the pierogi for about 10 to 12 minutes. Then you'll drain them.
Once this kielbasa's cooked, add everything together and stir.