Instructions

1. 1

   Heat the oven to 400°F. Pat the pork tenderloin dry and season all over with the kosher salt and black pepper (about 5 minutes).

2. 2

   Heat the olive oil in a 12-inch oven-safe skillet over medium-high heat. Sear the pork for 2 minutes per side, turning to brown all sides, then transfer it to a plate. It's ready when the exterior is evenly browned.

3. 3

   Reduce the skillet heat to medium. Add the onion and apples and cook for 4 minutes, stirring once or twice, until the onion begins to soften and the apple edges take on color. It's ready when the onion is slightly softened and the apple edges are lightly browned.

4. 4

   Stir the thyme, apple cider, Dijon mustard, and maple syrup into the skillet. Return the pork to the center and spoon some of the cider mixture over it (about 2 minutes).

5. 5

   Transfer the skillet to the 400°F oven and roast for 6 minutes. Check the thickest part of the tenderloin with an instant-read thermometer; continue roasting briefly if needed until it reaches 145°F. It's ready when the thickest part registers 145°F on an instant-read thermometer.

6. 6

   Transfer the pork to a cutting board and let it rest for 3 minutes. Stir the butter into the hot apple-onion sauce, then slice the pork and serve with the apples and onions. It's ready when the butter is melted into the sauce and the pork has rested for 3 minutes.

Used in this recipe: Cast-Iron Skillet · Instant-Read Thermometer (Amazon, affiliate links)