I think Pho Tai is the best and seriously, the most authentic across Hong Kong and you know why? On each table inside this chain of restaurants you will find a basket of herbs featuring not only the pho essentials like mint, basil, lime and beansprouts but most importantly, they also have "Ngò Gai" or "Rau Gai" (Sawtooth Herb in English) therefore elevating this restaurant's level of know how and authenticity
Pho Tai is also great value and there are chains all over HK so enjoy!
PS Anyone know of any Vietnamese Courses in Hong Kong? I can speak it on a general level but I need to improve on my professional and business Vietnamese for a project my company is working on.