Pretty uncanny, someone else just wrote about this little find in the back of Thai Express. I'm pretty sure I found it first though lol, and have been meaning to write about it for a while now.
Anyways, true enough - they have several (freshly, hand prepared banh mi sandwiches for $4). With mini baguettes that are ironically larger than the average banh mi bun, warmed all the same, and placed in a bag and twist "tape" tied. They have a few authentic flavours, that take a little more adventurous palate. I imagine they're good nonetheless, as made by a woman from the region.
Be aware that they only take cash or debit, and at that for a minimum of $5, so just grab a drink or a banana cake square for 1.50. You'll be good to use plastic and have dessert all at the same time.