Ingredients
For Horseradish Sauce
Directions
Sprinkle roast with 1 tablespoon salt, cover with plastic wrap, and let stand at room temperature 1 hour or refrigerate for up to 24 hours. Adjust oven rack to middle position and heat oven to 400 degrees.
Toss bread crumbs with 2 teaspoons oil, 1/4 teaspoon salt, and 1/4 teaspoon pepper in 10-inch nonstick skillet. Cook over medium heat, stirring frequently, until deep golden brown, 3 to 5 minutes. Transfer to rimmed baking sheet and cool to room temperature. Once cool, toss bread crumbs with crushed potato chips, scallion, garlic, 2 tablespoons horseradish, parsley, and thyme.
Pat exterior of tenderloin dry with paper towels and sprinkle evenly with remaining teaspoon pepper. Heat reserved tablespoon oil in 12-inch nonstick skillet over medium-high heat until just smoking. Sear tenderloin until well browned on all sides, 5 to 7 minutes. Transfer to wire rack set in rimmed baking sheet and let rest 10 minutes.
Combine remaining 2 tablespoons horseradish, mayonnaise, and mustard in small bowl. Just before coating the tenderloin, add the gelatin and stir to combine. Spread horseradish paste on top and sides of meat, leaving bottom and ends bare. Roll coated sides of tenderloin in bread-crumb mixture, pressing gently so crumbs adhere in even layer that just covers horseradish paste; pat off any excess.
Return tenderloin to wire rack. Roast until instant-read thermometer inserted into center of roast registers 120 to 125 degrees for medium-rare, 25 to 30 minutes.
Transfer roast to carving board and let rest 20 minutes. Carefully cut meat crosswise into 1/2-inch-thick slices and serve.