Combine all marinade ingredients in a small bowl and whisk to combine.
Add pork tenderloin to a large resealable bag and pour marinade over top then seal the bag and shake to coat the pork. Refrigerate for at least 30 minutes, up to overnight.
Preheat oven to 425°F. Line ⅓ of the sheet pan with foil and fold up the edge to make a lip separating the open end of the pan.
Add the marinated tenderloin to the foil lined section of the pan and pour the marinade over top.
Toss the potatoes in the olive oil, salt, pepper, Italian seasoning, and Parmesan cheese then add to the other half of the pan, cut side down.
Bake in the oven for around 25-30 minutes until the pork reaches an internal temperature of 140°F. Remove the sheet pan from the oven and set to broil then flip the potatoes and return the pan to the oven. Broil for 2-3 minutes keeping a close watch to avoid burning. Let the pork rest for 5 minutes before slicing and serving.