Combine seasoning ingredients in a small bowl and set aside.
Use a sharp knife to cut the pork into 3 to 4 large pieces and trim off any large pieces of fat.
Sprinkle the seasoning mix all over the pieces of pork and rub it in making sure it is evenly distributed on all sides of the meat.
Turn on the Instant Pot to the sauté function and add oil. Once hot, add the pork and sear for 2 to 3 minutes on each side, or until a crust has formed. Repeat with remaining pork if needed.
While the pork is sauteeing, whisk together the tomato sauce, dark brown sugar and apple cider vinegar in a medium bowl.
Turn off the instant pot. Pour the sauce over the pork and then place the lid on the instant pot and lock it into place.
Cook the pork using the meat/stew function for 60 minutes or until the pork easily pulls apart with two forks.
Once the pork has finished cooking, release the steam using the quick release valve to manually release the pressure.
Transfer the pork to a large plate and shred using two forks. Toss the pulled pork with some of the sauce in the instant pot and/or toss with your favorite BBQ sauce.
Serve on buns with coleslaw and bbq sauce, optional.