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 internal thermometer, about 20 minutes. Remove from oven and let rest for 15 minutes before slicing and serving.