In skillet over medium heat, heat oil. Sear pork loin on all sides.
In slow cooker, stir cranberry sauce, dried cranberries, orange juice, cinnamon and orange zest until combined.
Set pork loin in middle of sauce mixture and drizzle sauce over meat. Cover and cook on low 4 hours, or until meat reaches 140-145 F.
Transfer pork to cutting board. Remove twine. Let stand for 5 - 10 minutes.
Strain cranberries from slow cooker; set aside. Pour strained liquid into skillet. Add salt and pepper, to taste. Simmer 7-8 minutes to thicken sauce to your preference.
Put pork loin on platter. Slice enough for first serving. Spoon cranberries and sauce over pork loin.