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