Spice rub: add the mustard powder, garlic powder, onion powder, smoked paprika, dried oregano, salt and black pepper to a small bowl and mix until consistently combined. Then set aside.
Pork tenderloin: working one fillet at a time place the pork in the centre of a clean and dry cutting board. Next use a sharp knife to remove the silver skin. Then repeat for the other tenderloin.
Spice mixture: next place both tenderloins on the chopping board and sprinkle the spice mixture over the pork. Use your hands to massage it in so that the pork is fully covered.
Sauce: liberally spray the slow cooker insert with cooking oil. Then pour in the chicken broth, barbecue sauce, tomato sauce and Worcestershire sauce. Stir to combine.
Cook then shred: place the 2 fillets of seasoned pork into the base of the slow cooker. Put the lid on and set the timer to 4 hours and the temperature to high. Let the pork cook for 3 hours to start with, At the 3 hour mark, take the lid off and transfer the cooked pork to a chopping board. Use 2 forks to pull the meat and then transfer the pulled meat back into the slow cooker. Stir to mix in the sauce. Then put the lid back on and cook for a further 30 mins to an hour.
To serve: serve the pork with toasted pita bread and salad. Try it in hamburger buns or as you see fit.