Season tenderloins with salt and pepper and brown in oil in a skillet for about 1 minute on each of 4 sides. Place in one layer in a 5- to 6-quart oval slow cooker with broth, wine and orange zest strips.
Cover and cook on low for about 1 1/2 to 2 1/2 hours, checking after 1 hour, until the thickest part of each tenderloin reaches 145°F. Remove ready pieces individually and rest for at least 3 minutes.
During the final 20 minutes, combine cranberries, orange juice, sugar and water in a saucepan. Simmer for 10 to 12 minutes, stirring, until most berries burst and the sauce thickens.
Discard orange zest strips from the crock. Skim the cooking juices and stir 2 to 4 tablespoons into the cranberry sauce to make it spoonable; simmer for 1 minute.
Slice rested pork across the grain and serve with a modest amount of warm cranberry-orange sauce over each portion.