Swirl to coat the bottom. Roast the pork for 10 minutes: Set the pork in the pan. (It's fine if your pork tenderloin is a little long for the pan; just bend it to fit as we did here.) Return the pan to the oven. Roast for 10 minutes.Flip the pork, reduce the heat, and roast another 10 to 15 minutes: Flip the pork to the other side.Reduce the oven temperature to 400°F and continue roasting another 10 to 15 minutes. The pork is done when its internal temperature registers 140°F to 145°F in the thickest part of the meat (20 to 25 minutes total).lip the pork, reduce the heat, and roast another 10 to 15 minutes: Flip the pork to the other side. Reduce the oven temperature to 400°F and continue roasting another 10 to 15 minutes. The pork is done when its internal temperature registers 140°F to 145°F in the thickest part of the meat (20 to 25 minutes total).