If you’ve ever put away a serving of house-fermented vegetables at a fancy restaurant or had a roommate taking up your counter space with a crock of slowly bubbling sauerkraut, it’s likely you have Sandor Katz to thank. The self-styled “fermentation revivalist” has become a globe-trotting mascot for the power of bacteria and yeast to create delicious food, a kind of modern-day Johnny Appleseed of tangy, savory flavors. Katz discovered fermented foods in the early 1990s when, after receiving an H.I.V. diagnosis, he moved from his hometown of New York City to a queer community in rural Tennessee, where preserving...