I think often good food comes in strip malls, especially in the DC area. Some of my favorite restaurants are good examples- Pasta Plus in Laurel MD, Huong Que in Falls Church, VA and Minerva in Fairfax, VA.
Tyler Cowen (a foodie and economist) credits low rents, since they ‘encourage culinary experimentation and attract immigrants.’
You probably have seen this, but if you haven’t his ethnic food guide is worth checking out.
It’s disorganized, but a great resource: http://www.gmu.edu/jbc/Tyler/ethnic.html