Into a bowl, add Smoked Paprika (1 tablespoon), Garlic Powder (1/2 tablespoon), Cayenne Pepper (1/4 teaspoon), Brown Sugar (1 teaspoon), Celery Salt (1/2 teaspoon), Dry Mustard (1/2 teaspoon), and Salt (1 teaspoon). Mix well, then set aside.
Rub the seasoning all over the Pork Shoulder (1 pound), including the fat side.
Into the slow cooker, add Chicken Stock (1/2 cup), then the pork, skin side down. Cook on low for 6-8 hours or on high for 4-6 hours, depending on the size of your pork and slow cooker.
When the pork has around 1 hour left, start making your sauce. Into a saucepan over medium-high heat, heat up Olive Oil (to taste) and add Red Bell Pepper (1). Sweat that down for several minutes.
Add Apple Cider Vinegar (3 tablespoon), Dijon Mustard (1 teaspoon), Brown Sugar (1 tablespoon), Salt (1/2 teaspoon), and Tomato Paste (1/4 cup). Simmer for 20 minutes.
Using a hand mixer or blender, puree the sauce until smooth. Transfer the mix to a bowl.
Carefully remove the pork. Strain the cooking juices and stock and set aside.
Slice the fat off the pork and place it back into the slow cooker. Using forks, shred the meat. Throughout this process, gradually add the cooking juices back in. Finally, add the sauce and mix through well.
To serve, heap the shredded pork on top of the Brioche Hamburger Bun (6).