Combine cider vinegar, ketchup, red pepper flakes, sugar, water, dry mustard, Worcestershire sauce, molasses, tomato paste, soy sauce, salt, and pepper in a stainless steel saucepan.

Bring the sauce mixture to a boil, then reduce heat and simmer for 10 minutes.

Remove the sauce from heat and let it cool completely before using.

Pour the cooled sauce into a bowl or jar for storage.

Cover the sauce and refrigerate until needed.

In a large saucepan, combine 1 quart of water with salt, soy sauce, honey, molasses, and sugar.

Bring the brine mixture to a boil over medium heat, then remove from heat and let cool.

Stir the remaining water into the cooled brine.

Pierce the pork butts in several places with a boning knife.

Add the pork butts to the brine.

Cover and refrigerate the pork in the brine overnight.

Remove the pork from the brine and coat it lightly with salt and pepper.

Arrange the pork butts in a smoker.

Set the smoker to 250F and smoke for 8 hours, adding applewood chips for smoke.

Remove the smoked pork from the smoker and place on a cutting board.

Shred the pork when cool enough to handle.

Arrange the shredded pulled pork on a serving platter and serve with the Carolina BBQ sauce.

Serve the pulled pork on fresh baked buns, if desired.