Using a sharp knife, trim all fat and silver skin from the tenderloins and set aside.

In a medium bowl, combine the mustard, vinaigrette and vegetable oil and whisk to combine. Transfer contents to a resealable plastic bag and add the tenderloins. Turn the tenderloins so that they are evenly coated with the marinade, then seal the bag, trying to remove as much air as possible. Refrigerate for 45 minutes before proceeding.

Preheat the oven to 400 degrees F. Heat a large saute pan or skillet over high heat. When hot, add the tenderloins and brown on all sides, turning occasionally to ensure even cooking, about 6 minutes. Transfer the pan to the oven and cook until the tenderloins are medium to medium-well, or registers 140 to 150 degrees F on a meat thermometer, about 8 to 10 minutes. Remove the meat from the oven and allow to rest for 5 minutes before serving. Slice the meat into 1/2-inch thick slices on the diagonal, and serve immediately, with some of the remaining Rosemary Apple-Vinaigrette spooned over the top.

Combine the apples, cider vinegar, shallots, sugar, rosemary and black pepper in a skillet and bring to a simmer. Reduce the heat to low, cover, and simmer until the apples are tender, about 6 minutes. Remove from the heat and transfer to a blender or food processor.

Add the mustard, soy sauce, kosher salt, and green onions, and puree on high speed. With the motor running, add the oil in a thin stream and process until emulsified. Remove from the blender and refrigerate in an airtight container until ready to serve. (The vinaigrette will keep for up to 1 week refrigerated.)