Season the pork with ½ teaspoon salt and ¼ teaspoon pepper.
Heat the oil in a large skillet over medium-high heat. Cook the pork, turning occasionally, until browned, 6 to 8 minutes.
Reduce heat to low, cover, and cook until cooked through, 15 to 20 minutes.
Meanwhile, melt the butter in a second skillet over medium-high heat. Add the apples and cook, stirring, until tender, 5 to 7 minutes.
Sprinkle the apples with the thyme and serve with the pork.