does anyone know of one in DC or NOVA??
Not like you would find in Poland.
The two restaurants in DC where you can reliably find some items are:
W Domku, which is part Polish part Scandinavian.
Restaurant Kolumbia, a posh downtown restaurant where the chef is Polish and includes one or two items on his otherwise upscale, refined menu.
I don't plan on running back to either place, but YMMV.
If you're willing to stretch to German fare, Old Europe in Glover Park is gloriously old-school.