Preheat the oven to 375 degrees F.
Mix 3 tablespoons olive oil, freshly ground black pepper, salt, orange zest, and minced rosemary in a small bowl. Rub the oil mixture all over the trimmed pork tenderloins and place them in a large baking dish
. Cover and let the pork marinate 20 minutes.
Heat the remaining 3 tablespoons oil in a large skillet over medium-high heat. Add the pork and sear
, cooking until browned on all sides. Remove the pork tenderloins from the skillet and place into an oven-safe dish; cover. Roast
the pork until a meat thermometer
inserted into the thickest part of the meat reads about 145 degrees F, about 15 minutes.
For the pan sauce: Pour off the majority of the cooking fat leaving any browned bits in the pan. Heat the pan over medium-high heat and add the shallot and the wine. Continue cooking until most of the wine has cooked off, scraping the browned bits off the bottom of the pan.
Add the broth and continue cooking until the sauce has reduced by half. Remove from the heat. Stir in the butter, one piece at a time, until fully incorporated.
Stir in the balsamic vinegar, rosemary, orange zest
, salt, and pepper, to taste. Let the pork rest for 10 minutes before slicing. Drizzle
with the balsamic pan sauce.