You see many food trucks come and go, and mostly you can't rely that they are going to show up everyday. But Saigon Sandwich is always there, which I can certainly rely to know that they will make my Vietnamese sandwich for me.
I work around the block and find the sandwich perfect for lunch. It's cheap ($4.95), fast, and a short walk (South Union cafeteria takes longer usually). You can pick so many kind of vegetables / topping (no extra charge) to go with it, simply indicating them on the order sheet. I have tried most of them so many times now. My favorite is banhmi (grilled pork and chicken) sandwich. The only thing that I complain about is probably the baguette is not as crispy as I hope it would be. Coming from New York, I have pretty high standards for my vietnamese sandwich crust! Otherwise I am happy and have been back so often since I have my first bite. And now they even accept apple pay, no excuse for no cash or even credit card!