Here's a link to the full-service (i.e. not fast-food) dining at Dulles: http://www.metwashairports.com/dulles/732.htm

In particular Vino Volo in the B Concourse has a very nice small-plate menu and good wine selections. It is just a few steps from the LH lounge, which also has quite decent food and bar offerings. I would check out both and then decide.

In addition, the A/B concourse (from A14 up to B79) has lots of nice shops and other food services.