Trim excess fat from the pork shoulder roast, leaving a thin layer for flavor and moisture.

Heat 2 tablespoons vegetable oil in a large skillet over medium-high heat. Once hot, add the pork roast and sear on all sides until nicely browned, about 2-3 minutes per side.

Transfer the seared pork to your slow cooker.

In the same skillet, reduce heat to medium and add chopped onions. Sauté until translucent, about 3-4 minutes. Add minced garlic and cook for another 30 seconds until fragrant.

In a medium bowl, whisk together ketchup, apple cider vinegar, brown sugar, tomato paste, Worcestershire sauce, Dijon mustard, smoked paprika, black pepper, salt, and cayenne pepper.

Add the sautéed onions and garlic to the sauce mixture and stir to combine.

Pour the barbecue sauce over the pork in the slow cooker, ensuring the meat is well coated.

Cover and cook on LOW for 8-9 hours or on HIGH for 4-5 hours, until the pork is extremely tender and easily shreds with a fork.

Once cooked, carefully transfer the pork to a large cutting board. Using two forks, shred the meat, removing any remaining fat pieces.

Skim excess fat from the sauce in the slow cooker. If you prefer a thicker sauce, transfer it to a saucepan and simmer for 10-15 minutes to reduce.

Return the shredded pork to the slow cooker and mix with the sauce. Keep warm until ready to serve.

Serve on toasted hamburger buns with a spoonful of coleslaw, if desired.