[mkoryak]

Somewhat unrelated: Can one buy kvass starter in the United States, and if so, what is it called?

I'm not interested in bottled kvass, it never tastes like the real thing and you don't get to watch kvass explosions in the bottle as it is being made

[richiebful1]

Kvass starter? I typically just use yeast, old rye bread, raisins, and sugar. Maybe added lemon for taste at the end.

This recipe is similar to how I make mine (in Russian): https://www.gastronom.ru/recipe/55100/domashnij-kvas-iz-hleb...

[mkoryak]

TIL.. When I saw kvass being made I was too young to know how it works.

[nibbleshifter]

You don't need a starter? You can just make one trivially.

There's a pretty amusing "Life of Boris" video that shows how on YT.