Preheat your oven to 400°F (200°C).
Season the pork tenderloin with salt and pepper.
Heat olive oil in an oven-safe skillet over medium-high heat.
Sear the pork tenderloin on all sides until golden brown, about 3-4 minutes per side.
In a separate bowl, whisk together apple cider, Dijon mustard, brown sugar, and thyme.
Pour the apple cider mixture over the seared pork.
Transfer the skillet to the preheated oven and bake for 20-25 minutes, or until the internal temperature reaches 145°F (63°C).
Remove the skillet from the oven, and let the pork rest for 5-10 minutes before slicing.
Slice the pork and drizzle with the remaining apple cider glaze from the skillet.