This pork tenderloin recipe roasts apples and acorn squash alongside for an easy, delicious weeknight meal. Preheated baking sheets help jump-start the roasting process, ensuring everything gets nicely browned.
Position racks in center and lower third of oven. Place a large rimmed baking sheet on each rack. Preheat oven to 450°F.
Toss squash with oil, 1 tablespoon sage and ¼ teaspoon each salt and pepper in a medium bowl. Place the squash, cut-side down, on one of the baking sheets. Add apples to the bowl and toss to coat with the remaining oil mixture; set aside.
Coat the other baking sheet with cooking spray and place pork on it. Sprinkle the pork with the remaining ¼ teaspoon each salt and pepper. Brush the top with mustard and sprinkle with Parmesan and the remaining 1 tablespoon sage. Place the pork on the lower rack and the squash on the center rack and roast for 10 minutes.
Add the apples to the pan with the pork. Flip the squash. Continue roasting until the squash is tender and an instant-read thermometer inserted in the thickest part of the pork registers 145°F, 10 to 15 minutes more.
Transfer the pork to a clean cutting board and let rest for 5 minutes. Pour vinegar around the apples and scrape up the browned bits. Toss the apples with the squash. Slice the pork and serve with the squash and apples.