Rub entire roast with spice rub and place fat side up in slow cooker.
Pour Dr Pepper into slow cooker.
Cover and cook on high for 7-8 hours or until meat falls off the bone.
Remove pork from slow cooker and place on a large rimmed baking sheet.
Using two forks, shred pork, removing excess fat and bone.
Place a helping of pork on roll and top with Spicy BBQ Sauce.
BBQ Sauce
In a large pot, saute onion in vegetable oil over medium heat until softened but not browned.
Add all other ingredients and cook for 10-20 minutes, or until sauce thickens to desired consistency.
Notes
I have substituted two pork tenderloins in place of the pork butt and it has turned out wonderful! I have also substituted two double chicken breasts in place of the pork and it’s wonderful, too! You can make the sauce ahead of time and reheat it when you’re ready to serve it. You can also add the shredded pork to the sauce and heat it together, if you’d like.