I was at SJSU on Saturday. I'm not familiar with the area at all. I noticed that on Santa Clara there are a number of signs in Vietnamese and the wheels in my head started turning.
Sure enough, I walked back a different route to my car in the afternoon. Yep. Its there. On Seventh St. at Santa Clara. The tiny "Cali Sandwiches" ("Cali" part was very faded) has Banh Mi starting at $1.50 for a Veggie up to $2.00 for Fancy Pork. The place was busy, they had five tables for eating in, and they had the signature "Banh Mi Shop" look of jam-packed refridgerator display cases with piles of containers of exotic (to me) foodstuffs. I cannot vouch for the quality because I was still digesting a huge lunch.
My next class at the SJSU campus is on March 16th so I will go then and report back. Unless, of course, some South Bay Chowhound beats me to it.