One of the greatest things about D.C. is the diversity of the population resulting in virtually all the world's culture/cuisine represented very well in the Metro D.C. Area.

Some good info in here.

http://www.gmu.edu/jbc/Tyler/ethnic.html - mostly standard to good to excellent places.

If you want to stick to D.C. - Adams Morgan has a great mix of Hole in the Wall , small boutique type restaurants from varying cuisines.

Bon apetit!