The Prosciutto & Anchovy Potato Sub is packed with slices of prosciutto topped with anchovy potato salad and additional veggies of your choice. Potato salad in a burger sounds pretty amazing in theory but if you're not big on anchovies maybe pass on this one. A six-inch sub will run you 490 yen (4.77 USD), if you happen to be in Japan act fast because this promo will end sometime this month.