In a heavy skillet, heat the oil and butter over medium-high heat. Sprinkle the pork tenderloin filet generously with pepper and thyme and cook for 3-5 minutes on each side, until golden and just cooked through (the middle should reach 160F). Transfer to a plate and set aside.
Sauté the apples in the pan for a few minutes, until starting to soften and turn golden. Add the mustard, maple syrup and cream and cook, stirring, until the mixture is well blended, comes to a simmer and thickens. Pour the apples and sauce over the pork and serve immediately.