Preheat oven to 475 degrees.

In a heavy skillet cook bread crumbs in 1 tablespoon oil with salt and pepper to taste over moderate heat, stirring, until golden brown. Transfer bread crumbs to a bowl and toss well with horseradish.

Pat pork dry and season with salt and pepper. In a skillet heat remaining tablespoon oil over moderately high heat until hot but not smoking and brown pork on all sides, about 5 minutes. Transfer pork to a shallow baking pan. In a small bowl, mix mustard and mayonnaise. Coat top and sides evenly with mixture. Press bread crumb mixture evenly onto mustard and roast pork in middle of oven until a meat thermometer inserted in center registers 145 degrees for slightly pink meat (if bread crumbs begin to get too browned arrange a sheet of foil loosely over pork), 25 to 30 minutes. Transfer pork to a cutting board and let stand 5 minutes.

Cut pork into 1/4-inch-thick slices. Serve with cabbage and onions (recipe follows) and boiled new potatoes with chive butter.