I know that my tour group offers a "box lunch" during the tour. Hoping that other RS members found a great deli/market/sandwich shop the day before and brought their own lunch. TIA
There is a cafe at the visitors center. We ate lunch in Krakow before our afternoon tour there, so we didn’t eat at the cafe. I grabbed a coffee at the cafe that was decent.
The breakfast buffet at my hotel [Wawel] was in the connected Black Duck restaurant, so I made a ham and cheese sandwich to take with me - ate it on the bus transfer to Birkenau. If you're on a tour, it may be rather regimented, without time allotted to stop at the cafe.
You could also grab several obwarzanek krakowski from a street vendor in Krakow.