Add the pork (fat side up) and onions to the slow cooker.
4 lb. boneless pork shoulder/pork butt, 1 small yellow onion, diced
Whisk the remaining ingredients together in a measuring cup.
1 cup apple cider vinegar, 1 cup ketchup, 3/4 cup dark brown sugar, 1/4 cup Worcestershire sauce, 2 Tbsp. yellow mustard, 1 Tbsp. kosher salt, 1 tsp. chili powder, 1 tsp. paprika, 1 tsp. garlic powder, 1/2 tsp. black pepper, 1/2 tsp. cayenne
Pour the sauce over the pork and onions. Be sure to get the pork nice and covered, tossing it once or twice if needed, keep fat side up.
Cover and cook on high 5-6 hours or low 9-10 hours. It should be fall apart tender, low and slow is the preferred option.
Trim and discard any fat, shred pork.
Carefully blend the liquid leftover in the slow cooker with an immersion blender. (Optional step: pass through a sieve to get the sauce nice and smooth)
Toss the pork in the liquid to keep the pork nice and moist. I usually add in some bbq sauce here at this step, too.
Serve as is with your favorite sides, build a sandwich or sliders with bbq sauce and your favorite toppings! Enjoy!
slider buns and desired toppings i.e. pickled onions, slaw, bbq sauce.