Hamburgers are hailed as the quintessential American food, but a struggle for differentiation is giving some of the newer versions a decidedly foreign accent.
U.S. restaurant chains have long tried to add an ethnic dash to their burger lineups by topping a patty with a few international elements and tagging the sandwich accordingly. Tomato sauce, pepperoni and fried mozzarella, for instance, figure heavily into Red Robin Gourmet Burger’s new
