Steam or nuke cored cabbage to soften. Chop into 1/4-1/2" pieces. Chop onions and the salt pork to same consistency. Place salt pork into large heavy skillet to brown. Add cabbage and onion [as much as will fit in skillet...or use two] and fry till all are brown. Salt and pepper to taste.

Spoon 1-2 Tb onto each round of perogie dough, moistene edges of dough with milk and fold perogie in half. Crimp closed with fingers & thumb. Drop perogies into large kettle of boiling salted water. Do not crowd. Perogies will float when cooked...approx. 5 mins. Morgan