Preheat oven to 425°. Cut tenderloin in half to fit skillet; sprinkle with salt and 1/4 teaspoon pepper. In a large skillet, heat oil over medium-high heat; brown pork on all sides. Transfer to a 15x10x1-in. pan. Roast until a thermometer reads 145°, 12-15 minutes.
Meanwhile, in same skillet, bring cider, syrup, vinegar and remaining pepper to a boil, stirring to loosen browned bits from pan. Cook, uncovered, until mixture is reduced to a glaze consistency, about 5 minutes.
Remove pork from oven; let stand 5 minutes before slicing. Serve with glaze.