I am surprised that no one has reviewed this cart yet, so I am taking the lead.
Saigon sandwich offers very delicious and inexpensive ($4.75) Banh Mi, which is the baguette sandwich that introduced during French colonial period. While colonialism is a ugly history, the culinary cultural exchange certainly created some most interesting food in the world. Banh Mi belongs to this category.
There are five choices of meat--veggie tofu, bbq pork, chicken, vietnamese meatball, and combo. You can also choose what fillings to be put onto your sandwich. The subway idea on a Vietnamese sandwich. The jalapenos are super spicy, be careful. I have tried bbq pork and chicken sandwich. Both taste good.
The cart is operated by a team from Pho Nam restaurant. I am happy to see it in the corner of Charter and Johnson. A great place to grad quick lunch if you're in the south side of UW campus.