1. Combine mayonnaise, yogurt, lemon juice, Worcestershire sauce and black pepper in small bowl until combined. Season with salt, to taste. Cover and refrigerate until ready to use. Do ahead: Dressing can be made up to 3 days ahead, stir before serving.
2. When ready to serve, layer roast beef on serving platter and top with drizzle of creamy black pepper dressing, baby arugula, shaved Parmesan, capers and pomegranate seeds. Tip: Save any leftovers for a sandwich the next day!