Season pork with salt and pepper on all sides. Drizzle oil into a large skillet and bring to medium heat on the stove.
Stir together brown sugar, Dijon mustard, garlic and apple juice. Rub mixture all over pork using your fingertips.
Cook pork in preheated and oiled pan, turning every 2-3 minutes to ensure even cooking. After about 10 minutes, add apples and cook until tender and pork is white enough through the middle (there shouldn't be any pink left).
Let sit about 10 minutes, then slice and serve.