Combine the buttermilk, Dijon, honey, sage, thyme, oregano, tarragon, sea salt, and freshly cracked pepper to taste, and minced garlic in a large zip-lock bag. Mix well, add the pork tenderloin, and seal. Refrigerate to marinate for at least 4 hours, preferably overnight.
Preheat the oven to 425 degrees.
Heat a large ovenproof skillet coated with cooking spray over medium-high heat.
Remove pork from the bag, draining excess marinade, and place in the hot skillet and cook for 3 minutes, browning the top.
Flip the tenderloin over and place it in the oven, and bake for 20-25 minutes or until the meat thermometer registers 145-150 degrees (medium) or until it reaches the desired degree of doneness.
Let stand for 5 minutes before slicing.
Place the slices on a serving tray, then pour the juice on the cutting board over the meat. Serve and enjoy.