Beef and Crisp Sweet Potato Roll

Beef is not a traditional filling ingredient for rolls, but this recipe proves that your favorite beef can be part of a delicious sushi roll. Here the juicy beef, which is seared and marinated in a Japanese broth overnight, is rolled up with crisp sweet potato and Western horseradish. Serve it with gyuniku no tsume, rich brown beef shoyu sauce. This roll is best when made medium-thick, so you get more beef and crispy potatoes. You could also use