Tons of tourists visit Washington, D.C. and I would like to lend some advise. I know when I visit an unfamiliar place, I like to get something distinctive and local to eat. What tastes like Washington, D.C.?
If you eat shellfish, get crabcakes, of course. We do them well here, even if it is technically a Maryland specialty. But if you're paying less than $12-15 for a small dinner portion, you're probably getting junk. But what else?
Some will point to the half smoke, a local sausage served in a bun, somewhere in taste and texture between a frankfurter and a bratwurst. I don't like them. People and guides will insist you visit the half smoke landmark, Ben's Chili Bowl on the once-desolate, now-vibrant U Street corridor. But I think it's repulsive: I've never come out of there when I didn't feel the twin pains of heartburn and regret.
For my money, I'd say that pupusas, a Salvadoran specialty conceptually between a tamale and a grilled cheese sandwich, is the best. Salvadorans moved into D.C. in waves after their civil war and now make up a conspicuous and important part of the local scene. Cheese ones are my favorite -- you can get pork, too -- and are usually served with a dab of vinegary slaw. They're not expensive -- you can usually get a serving for $2 or $3 -- but can be quite filling. Allow some time, as they take time to grill. The best I've had in an area close to local hotels is La Frontera Cantina but if you keep your eyes open any "Mexican" restaurant or take-out will have them.