Mei Sum probably has the best overall bahn mi in Boston, but if the original poster is still in the area, he should check out Lu Lu’s sandwich shop (diagonally across from Mei Sum) for their awesome meatball bahn mi. It’s attached to a jewelry store (sound familiar?) That is hands-down the best bahn mi I’ve had anywhere, but if you’re not in the mood for meatballs, Mei Sum’s is better.

http://www.comestiblog.com/weblog/2008/05/bx-hits-the-spo.html

there are like 10 other places in that food mall alone that makes good banh mi…just saying for all you viet food lovers, this place is worth the pilgramage. i grew up going here every weekend…just look through the site at all the restaurants and ull see what i mean. fortunately im going home this week for thanksgiving so im definitely bringing buy 5 get 1 free back to brooklyn with me. they pack all the pickles and cilantro on the side for u, so the sandwiches are good for a few days.