1. Heat oven to 450 degrees. Place two baking sheets in oven. Peel potatoes; cut into 1/4-inch sticks. Place in a bowl; toss with olive oil, 1 1/2 teaspoons salt, and 1/4 teaspoon pepper. Carefully remove baking sheets from oven; coat with cooking spray. Divide potatoes between the hot baking sheets in a single layer. Bake, tossing occasionally, until golden brown, 20 to 30 minutes.

2. While potatoes are cooking, heat a cast-iron or heavy skillet over medium heat until very hot. Place filet slices in a layer of plastic wrap; lightly pound with the flat side of a meat tenderizer until 1/2 inch thick. Season steaks on both sides with remaining 1/2 teaspoon salt and 1/4 teaspoon pepper. Sear in hot skillet until browned on both sides and medium rare in center, about 2 minutes per side. Serve immediately with fries and Dijon mustard.