Although this thread trends more towards fancy, pricey foods, I have one restaurant to suggest: Panjshir. With two restaurants in the DC area, Panjshir serves absolutely incredible Afghan food that is also really reasonably priced. What's also nice is that they are a family run business and as my family has gone there for the past 20+ years, I get a greeting from the owner every time I go. One caution though, the service there is incredibly slow, even when the restaurant is empty.