Preheat the oven to 400° F. Line a sheet pan with foil and set aside.
Place a large cast-iron skillet over medium-high heat. When the skillet is hot, add 2 tablespoons olive oil. Once the oil is shimmering, add in the pork tenderloin and sear on one side for 2 minutes, or until you’ve got a nice golden crust (it should be easy to flip).
Continue to sear the remaining sides for 1 to 2 minutes per side, until the whole tenderloin is well-seared.
In a medium-size bowl, stir together 1/4 cup orange juice, the apple cider vinegar, marmalade, and cranberry sauce.
Place the seared tenderloin in the middle of the sheet pan. Spread half of the sauce over the tenderloin. Roast for 25 to 35* minutes, or until the internal temperature reaches 145° F.
Meanwhile, toss the green beans with the remaining tablespoon of oil, plus salt and pepper, to taste.
After *10 minutes of roasting, remove the tray and add the green beans all around the pork. Return to the oven.
Once the pork is done, remove from the oven, tent the pork with foil and let stand for 10 minutes before slicing.
While the pork is resting, take the remaining 2 tablespoons orange juice and the remaining sauce and place in a small pot over medium-high heat. Bring sauce to a boil and then reduce to a simmer while pork rests.
Serve pork tenderloin slices with reserved sauce and enjoy. Garnish with fresh rosemary and cranberries if desired.