1. Preheat oven to 400°. Whisk together first 2 ingredients.
2. Place rolls on a baking sheet. Bake at 400° for 5 minutes or until lightly toasted but still soft. Let cool 10 minutes; split rolls.
3. Spread cut sides of rolls with mayonnaise mixture. Layer bottom roll halves with beef, folding slices as needed to fit rolls. Top each with cheese, arugula, and remaining roll halves, mayonnaise mixture sides down.