Pre-heat the oven to 375°F.
In a large resealable plastic bag, combine the wine, stock, vinegar, Worcestershire sauce, garlic and Dijon mustard. Season the meat with salt and pepper and add to the marinade. Refrigerate the steaks for 4 hours.
Soak the potatoes in salted water in a large bowl for a few minutes. Drain and pat dry.
Toss the potatoes with about 3 tablespoons olive oil and season with the thyme, salt and lots of peppercorn blend. Place the potatoes on a baking sheet and bake for 20 minutes, then remove and cool to room temperature.
Heat a cast iron or ovensafe skillet over medium high heat.
Pat the steaks dry and coat evenly with a couple of tablespoons olive oil. Brown the steaks on each side to caramelize, then transfer to the oven and roast until desired doneness; remove to rest.
Turn up the oven to 450°F and bake the potatoes until deeply golden and crispy, 20-25 minutes.
Serve the steak with an arugula and tomato salad alongside.