89 Hang Bac
Just as its name: Ancient Town, this restaurant is located on an very old street of Hanoi and also offers Vietnamese traditional food. Moreover, the restaurant is simply and elegantly decorated and will bring you the most comfortable feeling.
From Hang Bo St, go down to Hang Bac St. Keep going until you pass the intersection of it and Dinh Liet St. The restaurant is nearby and on the right hand side of the street.