In a small bowl, mix the vinegar, mustard and herbs together. Reserve mustard sauce for pork.
In a large ovenproof saute pan over medium-high heat, warm the vegetable oil. Sear pork loin on all sides. Brush with mustard sauce and roast in the preheated oven until the internal temperature reaches 145 degrees F on an instant-read thermometer, about 20 minutes. Remove from oven and let rest for 15 minutes before slicing and serving.