Preheat the oven to 325°F
Place the pork tenderloin in a baking dish
Add a small amount of broth, water, or pan juices
Cover the dish tightly with foil
Heat for 15 to 20 minutes, or until warmed through
Check that the internal temperature reaches 165°F
Let it rest for a few minutes before slicing
Reheat slices in a skillet over low heat if preferred
Use a microwave only on low power in short intervals
Avoid overheating to prevent the pork from drying out