Season pork with black pepper; set aside. In an oven-proof skillet over medium-high heat, add oil. When hot, place pork and cook on one side until brown. Flip and transfer in a 375ºF preheated oven; cook for 18-22 minutes depending on the size of the loin. When internal temperature reaches 140-145ºF, remove from the heat and place tenderloin on a board with a folded sheet of aluminum on top to keep warm.
Return skillet on the stove and remove excess oil. Add clarified butter and turn the heat to medium. When hot, add onion and sauté for 2 minutes. Add garlic, ginger and rosemary; sauté for 1 minute. Pour white wine to deglaze the bottom of the pan, scraping any brown bits.
When liquid is half reduced, add maple syrup, mustard and cayenne pepper; stir and cook the sauce down until turns into syrupy texture, about 8 minutes. Spoon it over the pork. 2 servings.