For the pork tenderloin: Place an oven rack in the center of the oven. Preheat the oven to 400 degrees F. Spray a heavy baking sheet with vegetable oil cooking spray. Set aside.
Sprinkle the pork with the salt and pepper. Heat the oil in a large skillet over medium-high heat. Add the pork and brown on all sides, about 8 minutes. Transfer the pork to the prepared baking sheet and bake until a meat thermometer inserted into the thickest part of the meat registers 160 degrees F, about 30 minutes. Allow the meat to rest for 10 minutes before slicing. Slice the pork into 1/4-to-1/2-inch-thick slices.
For the honey mustard: Heat the oil over medium-high heat in the same skillet used for browning the pork. Add the shallots, salt and pepper. Cook until the shallots are soft, about 3 minutes. Add the garlic and cook until aromatic, 30 seconds. Add the wine and scrape up the brown bits that cling to the bottom of the pan with a wooden spoon. Cook for 1 minute. Whisk in the honey, mustard, vinegar and thyme. Simmer until thick, 2 minutes. Stir in the butter until melted and smooth. Season with salt and pepper.
To assemble the sandwiches: Slather the honey mustard on the cut sides of the baguettes. Arrange the pork slices in a single layer on the bottom halves of the baguettes. Spoon a little more honey mustard on top of the pork. Place the remaining baguette halves on top and serve. Serve any extra honey mustard alongside.