Preheat oven to 425°F. Spray a large, rimmed sheet pan with non-stick cooking spray.
In a small bowl, combine brown sugar, smoked paprika, thyme, garlic powder, salt, and cayenne pepper.
Arrange pork in the center of the sheet pan. Rub evenly with about 1 tablespoon of spice mixture.
Place carrots, apples, and onion in a large bowl. Toss evenly with olive oil and remaining spice mixture. Spread in a single layer around pork on the sheet pan.
Roast 25 minutes, or until pork reaches a minimum internal temperature of 145°F, tossing the carrot mixture halfway through. Let pork stand 5 minutes before slicing.
Serve pork over carrots, apples, and red onion.

Approximate nutritional values per serving (3 ½ ounces pork and 1 cup of carrots, apples, and onion):

300 Calories, 8g Fat (2g Saturated), 90mg Cholesterol, 440mg Sodium, 26g Carbohydrates, 6g Fiber, 16g Sugars (3g Added Sugars), 31g Protein