Hi, the correct spelling is banh trang (the "h" goes after the "n" -- counterintuitive to American spelling). I recommend the Eden Center, the mecca of the Vietnamese community in the DC area. It's at Seven Corners in Falls Church on Wilson Blvd. Several grocery stores at in the complex. In Maryland, I suggest Maxim Supermarket, a Chinese grocery up in North Rockville where Rockville Pike (355) turns into Hungerford Road. It's just north of Rockville town center. You might also get lucky at Korean Korner at the corner of Viers Mill Road and Randolph Road in Kensington/Rockville.