Dough: Place all ingredients in the bowl of a stand mixer. Using the dough hook, mix for 5-6 minutes on medium speed until stiff, not sticky, dough is formed. If you do not have a mixer, mound the flour. In the center make a well, place remaining ingredients in the well. Use a fork to slowly incorporate all of the flour into the liquid. Knead for 8-10 minutes until smooth. Cover dough with plastic wrap and refrigerate for 20-30 minutes to rest.
Filling: Place the pork, carrot, celery, cooking onion and stock in a dutch oven. Cook at 250 degree oven for 3-4 hours. Let cool. Strain and reserve the braising liquid. Place bacon in a saute pan over medium heat. Stirring to prevent burning, render the fat from the bacon (if not enough fat is rendered, add 1 Tbsp butter). Stir in onion, apple, seasonings and sugar. Cook until just taking on color. Add 1 cup of reserved braising liquid and reduce until very little liquid remains. Let mixture cool. Shred the cooled pork using a fork or your fingers. Combine with apple & onion mixture. Mix well.
Pierogies: On a well floured board, roll out 1/4 of the dough to about 1/16 inch thick. Cut out circles using cookie cutter or upturned glass. Place a small amount of the mixture in the center of each circle of dough. Fold the pierogies in half and seal the edges with the tines of a fork. Repeat untill all dough and filling is used. Drop a few pierogies at a time into salted boiling water. When they begin to float, remove from water and drain on paper towels. Refrigerate to chill. Saute pierogies in butter until nicely colored. Serve with braised red cabbage and sour cream.
Place all ingredients in a large stock pot over low heat. Stirring occasionally, cook covered until cabbage softens (about 2 1/2 - 3 hours). Serve hot.