Step 1

Preheat oven to 450°F. In a medium saucepan bring 3 cups water to boiling. Add onions; boil for 1 1/2 minutes. Drain and rinse with cold water. Slice off root ends; slip off and discard skins. Set aside.

Step 2

In a large bowl combine potatoes, oil, 1 tablespoon of the spice mix, and 1/2 teaspoon of the salt. Toss to mix. Spread cut side down in a a single layer in a shallow baking pan. Roast, uncovered, for 15 minutes. Add onions to baking pan with potatoes. Roast for 15 minutes more or until vegetables are tender and browned. Remove from heat. Cover with foil and keep warm.

Step 3

Preheat broiler. Rub steak with remaining 1/2 teaspoon salt and remaining spice mix. Place steak on the unheated rack of a broiler pan. Broil steak 4 to 6 inches from the heat for 5 minutes per side or until desired doneness (160°F for medium doneness). Transfer steak to a cutting board; cover and let stand 5 minutes.

Step 4

Carefully add wine to hot broiler pan, scraping up browned bits. Transfer sauce to a small saucepan. Bring to boiling and boil gently, uncovered, for 3 minutes or until liquid reduces to 1/2 cup. Remove from heat and gradually whisk in butter, a few pieces at a time. Whisk in any juices on cutting board from steak.

Step 5

Slice steak and arrange on plates with potatoes and onions. Pour on sauce and top with parsley, horseradish and lemon peel.