To prepare the pork tenderloin with apples and sweet potatoes, you'll first need to cut it in half lengthwise. Place the cut side down on a cutting board. Cut the meat into 12 inch thick slices. Season the slices with salt and pepper, and place them on the baking sheet. Bake in the oven at 450? for 1 hour and 15 minutes, or until the apples are tender and the potatoes are cooked through.