Trim tenderloin if needed, but leave whole.
In medium bowl mix sugar and vinegar, stirring until sugar is dissolved.
- Add oil and mix well.
- Add potatoes, carrots and toss to coat.
- Spread the potatoes and carrots out in a baking dish large enough to hold everything easily.
- Coat tenderloin with remaining vinegar/sugar and place in center of pan, with vegetables around it.
- Bake, uncovered, in 400F (200C) oven for 20 minutes.
- After 15 minutes, cut and core apple. Slice into thick wedges.
- Melt butter in nonstick skillet, add apples and toss to coat well.
- Remove pork and vegetables from oven.
- Turn the pork and stir the vegetables, turning them also.
- Arrange the vegetables in a single layer, with pork on top of some of them, in the center of the pan.
- Lay the apple slices around the vegetables and return it all to the oven for the last 20 minutes.
- Remove, let the pork rest while you arrange the potatoes, carrots and apples on a small platter.
- Slice the pork and place on top.
- Pour over any pan juices and serve.