Preheat the oven to 350 degrees F.
In a small bowl, mix together the olive oil, Essence, 1/2 teaspoon cracked black peppercorns, and 1/2 teaspoon salt, and spread evenly over the tenderloin. Heat a large ovenproof skillet over medium-high heat. Add the tenderloin and sear on all sides. Transfer to the oven and roast for 25 minutes for medium-rare. Remove from the oven and let rest for 10 minutes. Cut the tenderloin into thin slices.
In a bowl, combine the mayonnaise, horseradish, lemon juice, remaining 1/4 teaspoon salt, and 1/4 teaspoon black pepper, and whisk to blend. Cover and refrigerate until ready to use.
In a medium-size mixing bowl, toss the arugula with the olive oil.
Generously spread both sides of the French bread with the horseradish mayonnaise. Top one slice with the sliced roast beef, tomato slices, arugula, and cheese shavings. Top with the remaining slice of bread and press down to close. Slice crosswise into individual sandwiches, and serve.
Yield: 6 servings