Preheat the oven to 400°F (200°C).

Pat the pork tenderloin dry with paper towels.

In a bowl, mix together the kosher salt, cracked black pepper, garlic powder, smoked paprika, dried thyme, and chili flakes.

Rub the spice mixture evenly over the pork tenderloin.

Heat the olive oil in a skillet over medium-high heat until shimmering.

Add the pork tenderloin to the skillet and sear on all sides for about 2 minutes each, until a crust forms.

Transfer the skillet to the preheated oven and roast for 10-15 minutes or until the internal temperature reaches 145°F (63°C).

Remove the skillet from the oven and add butter and minced garlic. Tilt the skillet to baste the pork with the garlic butter for 1 minute.

Transfer the pork to a platter and tent with foil. Rest for 8 minutes.

Slice the pork against the grain into 0.5-inch medallions and serve.