There are two main sauces that goes on Pho: the black sauce is Hoisin sauce, and the red sauce is Sriracha - you might recognize the red rooster logo on Sriracha.If you've had Peking duck dishes at authentic Chinese restaurants, it is commonly served with Hoisin sauce. Sriracha has made its way into mainstream food establishments - you might find it on chicken wings, and on subs at sub shops.