Austin Graff
Google
Along Pennsylvania Ave SE literally steps from the Library of Congress is Dos Toros Taqueria, a New York-based fast casual burrito spot with several locations in the city. Walk inside and order a mission-style burrito, rice bowl, or salad with your pick of meat, toppings, sauces etc.
For lunch, I ordered chips and their queso blanco, a burrito with carnitas and all the toppings, and a Mexican Coke. It was very filling.
There's street parking nearby. The Capitol South Metro is close by.