There have been several chowhounds looking for BANH MI in Southern New England.
The food reviewrs at today's Hartford Advocate reviewed MINI SAIGON at 2014 Park Street in Hartford. They were very positive and noted that the restaurant served a very respectable BANH MI.
There are a bunch of hole in the wall Asian places in Hartford where I have seen them around. A Dong in West Hartford has them but I didn't think theirs was very good. This is an old thread on the topic:
I'll have to dig around, I thought fairly recently there was a thread on this board discussing banh mi in Hartford. If I find the thread I'll post it here.