Horseradish-Crusted Beef Tenderloin

"A crisp horseradish crust contrasts nicely with the mild flavor of beef tenderloin, but most horseradish-crusted recipes are uninspired and when carving time comes around, the crust falls off the meat in patches. We wanted to combine the bracing flavor of horseradish with a crisp, golden crust that would add textural contrast to rosy, medium-rare meat—and we wanted it to stick. We chose to use a center-cut roast—also called a Châteaubriand—because its uniform shape cooks evenly. After lightly flouring the meat and applying a thin wash of egg white, we rolled the roast in crushed potato chips and panko bread crumbs flavored with horseradish, mayonnaise, mustard, minced shallot, garlic, and herbs. Potato chips may seem unconventional but they kept their crunch and contributed an appealing, salty potato flavor. In order to avoid store-bought potato chips’ processed taste, we made our own by frying shredded potato in oil until browned and crisp. To make the crust adhere to the meat after being sliced, we replaced the egg white with gelatin. Because both meat and gelatin are made up of linear proteins that form tight bonds with each other, the gelatin mixture bound the bread crumbs firmly to the meat, yet yielded slightly as we cut it. And to prevent the crust from turning soggy from meat juices released during cooking, we seared the meat in a hot skillet and let it rest so that its juices could drain off before applying the paste and the crumbs. Then we coated only the top and sides of the tenderloin, leaving an “opening” on the bottom for meat juices to escape as it roasted...."