Cut the baguette in half lengthwise and hollow out both halves.
Heat some oil in a pan and cook the pork tenderloin all the way through.
Chop up the rosemary and sage, add salt, pepper, and minced garlic, and mix everything together. Brush the pork fillet with mustard and roll it through the herb mixture until it is completely coated.
Place the seasoned pork tenderloin in the hollowed-out portion of one of the baguette halves.
Secure the stuffed baguette with cooking twine and bake at 325°F for 15 minutes.