What type of beer should be used in making Beer Soup (Polewka Piwna) I've seen quite a few recipes for this old Polish soup based on beer, egg, cheese and some other ingredients but all of them call for "beer" or at best "light beer". I don't doubt most make a rather tasty dish but I'd like to aim at historical accuracy. While probably Seasoned Advice will be good with the rest of ingredients, I'd like to ask about the beer choice:

Which of beers currently in trade would most resemble what was brewed in Poland 300-500 years ago? What traits, properties, brands should I look for, that are most true to the antique recipes?
A saison would be the closest if you want "authenticity". This soup was usually a breakfast dish made with very weak farmhouse style ale often served to farm workers. The beers were locally brewed often by the farmers themselves. It only had about 3-4% abv so even today's commercial saisons have a bit more (5-8% abv). Sometimes kvas was used. Kvas is a light brew made from fermenting stale/dried bread (1-3% abv).