Pork Tenderloin with Apples and Onions

Pr0n tenderloin is more like it - this stuff  is disgustingly delicious.  Thanks Epicurious - for blowing my recent pork tenderloin with onion and apple relish right out of the water.

1 large pork tenderloin (about 14 ounces)
3 tablespoons olive oil, divided
2 tablespoons Dijon mustard
1 large onion, sliced
2 medium Granny Smith apples, peeled, cored, sliced 1/4 inch thick
1/2 cup dry white wine or apple cider

Preheat oven to 450°F. Season pork with salt and pepper.

Heat 2 tablespoons oil in large nonstick ovenproof skillet over medium-high heat. Add pork and sear until all sides are brown, turning occasionally, about 5 minutes. Transfer pork to plate. Cool slightly. Spread mustard over top and sides of pork. Add remaining 1 tablespoon oil to skillet. Add onion slices and apples; sauté over medium heat until golden, about 5 minutes. Spread evenly in skillet and sprinkle with salt and pepper. Place pork atop apple-onion mixture.

Transfer skillet to oven and roast until apple-onion mixture is soft and brown and meat thermometer inserted into center of pork registers 150°F, about 15 minutes. Transfer pork to platter and tent with foil. Let stand 5 minutes.

Meanwhile, pour apple cider over apple-onion mixture in skillet. Stir mixture over high heat until slightly reduced, about 2 minutes. Cut pork on diagonal into 1/2-inch-thick slices. Spoon apple-onion mixture onto plates. Top with pork and serve.