Preheat oven to 425 degrees and grease a sheet pan. Line one half of the sheet pan with foil, folding up the sides about 2 inches from the edge to make a "tray" (to prevent pork juices from spilling out). Place tenderloin in the center of the foil tray.
Pat tenderloin dry with a paper towel. Whisk together brown sugar, garlic, soy sauce, balsamic vinegar, red pepper flakes, and paprika. Pour over pork tenderloin, then turn the tenderloin over a couple of times to make sure all sides are coated.
Arrange potatoes on the other half of the sheet pan (non-foil half). Drizzle with oil, toss to coat, then season with salt and pepper to taste, Italian herbs, garlic powder, and parmesan cheese.
Bake in preheated oven for 20-25 minutes, using tongs to turn the pork over in the sauces every 5-10 minutes. *I like to switch the oven to BROIL for the last 2-3 minutes to brown the pork and potatoes - but watch carefully so it doesn't burn! Allow pork to rest for 5 minutes before slicing into 1-inch sections and serving.