Washingtonian has a helpful list of food truck locations for lunch every day. Over at 20th and L St, I found Hula Girl, Goodys and DC Ballers. Checking out the lines at each, I tried DC Ballers since it had the shortest line and the sun was blazing.
Falafel, fries, hummus in sandwich form or platters.
I ordered a falafel sandwich and fries.
The falafel had a good flavor, the pita was fluffy, and the filings included a nice spicy kick.
I think the best falafel sandwich I ever ate was in Israel, but this was a solid rendition. Nice staff and good flavor, I would recommend trying this food truck if it visits a location near your office.