From left: blueberry water kefir, coconut water kefir, hibiscus-ginger water kefir. [Photograph: Ed Anderson]

Milk kefir is a pretty common sight in the dairy aisle these days—or at least it is in California. Much more mysterious is its lactose-free cousin, water kefir. Both drinks are fermented with similar SCOBYs (symbiotic colonies of bacteria and yeast), but milk kefir grains feed on the natural sugars in the milk while water kefir needs additional sugar or fruit juice to get going. Mary Karlin provides recipes for both in her new cookbook, Mastering Fermentation. Today, we're trying our hand at the water-based version.

Why I picked this recipe: I was super curious what water kefir would actually taste like. Would it be sour like kombucha? Yeasty like good beer? Flat and weird? I had to try it.

What worked: Despite working with unfamiliar ingredients, this was a super easy project. The plain water kefir was slightly sweet and slightly yeasty, but ultimately pretty boring. Once I jazzed it up with a few pieces of ginger, however, I loved it. The ginger transformed the beverage into a barely sweet soda and a perfect thirst quencher.

What didn't: You don't need to use fancy glass bottles to store the finished kefir if you don't have them. Clean mason jars work just as well.

Suggested tweaks: You will need to source water kefir grains for this recipe. I ordered mine online from Cultures for Health and they worked great. I have also heard of friends having success finding kefir grains on Craigslist, but it's hard to verify how well they've been taken care of. You can flavor your water kefir in one of two ways. First, you could put the hydrated grains into fresh fruit juice or coconut water instead of plain water. Or you can add small pieces of fruit, vegetables, or tea leaves (like blueberries, ginger, or hibiscus) to the kefir once you've strained out the grains. The additional sugars from these additions will make the kefir lightly carbonated. If you want to use the kefir as a starter culture, leave it plain.

As always with our Cook the Book feature, we have five (5) copies of Mastering Fermentation to give away this week.

About the author: Kate Williams is a freelance writer and personal chef living in Berkeley, CA. She is a contributor to The Oxford American, KQED's Bay Area Bites, and Berkeleyside NOSH. Follow her @KateHWiliams.

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