Sprinkle the tenderloin with salt and pepper. Set aside.
Heat olive oil in a large frying pan over medium heat, and brown each side of the tenderloin.Place the tenderloin in the slow cooker, and turn the temperature to low.
In a small saucepan, combine cranberries, water and maple syrup and bring to a boil. Cook for about 5 minutes or until cranberries begin to split. Reserve about ½ cup of cranberry sauce for serving.
Slowly add the orange zest, juice, and balsamic vinegar into the remaining cranberry sauce. Stir until well mixed then pour over the tenderloin in the slow cooker.
Slowly add the orange zest, juice, and balsamic vinegar into the remaining cranberry sauce. Stir until well mixed then pour over the tenderloin in the slow cooker.
Let rest 10 minutes before slicing. Serve with reserved ½ cup cranberry sauce on top and additional orange zest, if desired.