Where can I find kosher kefir grains? Or does kefir grains not need a certification?
I am interested in making my own kefir drink. I'm in NYC if that helps. Thanks.
It does need certification, and I don't know where you can get it. However, here's a helpful hint: if someone takes any kefir grain and cultures milk with it, then takes the grain from that and cultures some more milk, then does this a third time, the grain from that 3rd culture will be kosher, and can be used to make kosher kefir. Note, however, that you can't deliberately do this; it's only good if it just so happened to have been done (e.g. by a friendly non-Jew).
Perhaps you can use existing kefir as a starter for your own? This is possible with yoghurt, but I don't know if the two processes are similar enough to do it. There are certainly kosher kefirs on the market to work with.