You have entered the lack of chow zone. There are usually several food carts around the 7th & Maryland, SW area, see FoodtruckFiesta.com. Other brick and mortars would be Vie de France, Atrium Cafe, Mitsitam Cafe in Museum of the American Indian, and National Gallery of Art. If you have a Fed Badge Dept of Energy has a good salad bar. More choices on other side of Mall in Penn Qtr if you have time.