-Palena has a great grass-fed burger.? Just steps from the Cleveland Park metro.? Some consider this the best restaurant in Northwest (Note: the back room is very expensive, the bistro in front--where they serve burgers--is not.)
-Dino, also in Cleveland Park, is paleo friendly, with good seafood selections, duck, and milk fed pork?(Italian style maialino).? Not especially cheap, but very good.?This is walking distance from my apartment and I eat here a lot!
-Bistro de Coin is a classic French bistro with many paleo options.? Fun?in the classic bistro style?(i.e. loud and crowded and lively) and prices are ok... if you don't get carried away with the wine.? This is my favorite?restaurant to take out-of-town guests.? Walkable from Dupont Metro.
-Nora is a pioneer in bringing organic, locally raised foods to DC, including grass-fed steak.? A little pricey, but a real treat.? Walkable from?Dupont Metro, but not exactly close.
-Founding Farmers is an easy walk from the Farragut West?station or the (somewhat farther) Foggy Bottom Metro and has?several paleo options including free-range chicken.? Have not been here yet, and would like to try it!
-The Reef is a fun place with a roof-top dining area in the heart of Adams Morgan.? Menu is small but strongly emphasizes local, organic, pastured meat.? I would highly recommend this for the Meet-up, except it's only somewhat Metro accessible--longish walk from Woodley Park.?
Georgetown (nothing in Georgetown is really Metro accessible, though the M Street strip is walkable from the Dupon Circle station--about 20 minutes at a brisk-ish pace, or the Foggy Bottom Metro, also?a pretty long?walk.? You can take a bus, but I don't know anything about that.)
-The Four Seasons serves a grass-fed burger with duck fries (delish, and the only fries I [ocassionally] allow myself since I went paleo) for $16--not bad for the Four Seasons!?? I'm not 100% certain that the burger is available for dinner--awaiting an email reply on this question.
-Hook is an excellent, but rather pricey, seafood restaurant that also serves grass-fed steak.? I've eaten here once and it was very good.? [Edit - grass-fed steak is mentioned in some reviews, but the steak on the menu does specifically mention grass.??But you should get the seafood, anyway!]
-Good Stuff Eatery?is reasonably priced and?_looks_ very?paleo friendly?from the menu (I've not eaten there).? They even have a "shun-the-bun" option for burgers wrapped in lettuce.? Walkable from Capitol South Metro.? It's not mentioned on the menu, but the restaurant replied to my email question that the beef is grass-fed.
-Sonoma is an easy walk from Capitol South; nice little place (I've eaten here) with grass beef and other paleo options.
-Elevation Burger is a popular inexpensive place serving grass-fed burgers.? Not really Metro accessible.
Old Town Alexandria
-Columbia Firehouse, walkable (though not very close) from King Street Metro, they have several paleo options and get their beef from local, pastured cows.