My grandfather was born in Rozwadow, a Polish shtetl between Krakow and Lublin, in 1907. He immigrated to Boston in 1931, making the crossing with little more than a goose-down duvet and a jar of schmaltz to his name. When I was a child, besides a ton of stories and an accent from central casting, he also shared with me his grandmother’s recipe for dill pickles. Those pickles formed a fundamental sense memory, ruining fluorescent deli spears forever. Watching him make them every summer gave me a primer in lacto-fermentation many decades before it became one of the defining trends in hipster gastronomy, though it would be many years until I put it to use.My grandparents both gardened enthusiastically; they had his-and-hers plots on the two sunniest spots in their yard in Waban, Massachusetts. She was the head chef, no doubt, but he reigned over the grill and the smoker (his chicken was divine), and he made the pickles. As the cucumbers grew, he’d pack them in various wide-mouth jars with copious garlic and dill, fill them with brine, and then ferment them in their basement. He used round rocks, pilfered from my grandmother’s flower garden and boiled to sterilize them, to weigh down the food and keep it submerged.Those steps taught me all I needed to know about this sort of fermentation. You need a brine, because lactic acid bacteria thrive in it and undesirable types do not. You need to keep the food below the surface so it doesn’t grow mold. And you need to ferment in a cool place. Those three facts are pretty much the whole story; the rest is details and personal preference. If you feel intimidated, remember: This is ancient, peasant technology. It may not be as bucolic as yoking oxen to plow a field, but you are enlisting billions of microbes to make your food tastier and healthier. It’s worth remembering that this technique for preserving vegetables—whether pickles, sauerkraut, or kimchi—was essential for survival in cold climates and remained an important preservation technique for poor immigrants who couldn’t afford refrigeration.It is also, in the words of fermentation guru Sandor Katz, “a strategy for safety”; there are no recorded cases of food poisoning from properly fermented vegetables. Beneficial halophilic (salt-loving) bacteria metabolize sugars and produce lactic acid, which lowers the pH and preserves the food. The combination of salt and acid makes fermented vegetables last indefinitely, adds a huge amount of flavor and beneficial probiotics, and can be achieved for pennies on the dollar relative to store-bought versions. Lacto-fermented pickles thus represent an extraordinary confluence of flavor, health, and economic benefits: truly a win-win-win situation.Aristotle lauded the health benefits of preserved cucumbers; Julius Caesar thought they imparted strength and stamina to his troops. This technique for preserving cucumbers (and other vegetables, and fish, and even meat) was and remains widespread in Eastern Europe. It’s not a specifically Jewish tradition. But as waves of Jewish immigrants transformed American cities in the 19th and 20th centuries, they brought these foods, which caught on in the wider culture. Over time “kosher pickles” came to refer to lacto-fermented cucumbers with plenty of garlic and dill.My grandfather’s pickles were beloved among his family and friends, and he was generous with them; when I went to college, my freshman roommate’s half of our little dorm fridge was stuffed with Busch beer. Mine held pickles. Later in life, when I moved to the Hudson Valley and began growing my own food, my grandfather’s recipe was my portal to fermenting. Over time, though, I did experiment with some variations to address two issues I had with his method. I’m happy to say that I fixed them, and the results clear the high bar he set with his efforts.First: salt. “I use a 5% brine,” I remember my grandfather saying once as he placed a freshly boiled rock into a jar. I found this to be a little high, and settled on 4% as ideal. I use a lower ratio in kimchi and other ferments, but a pickle should be assertively salty. Whatever your desired salinity, a scale and the metric system make it super easy to achieve since 40 grams of salt per liter of water (which weighs 1,000 grams) is 4%.Second: texture. His pickles were nice and crunchy after a month or so of fermenting, but got mushy over time. A little research revealed different Eastern European traditions of adding oak, grape, or horseradish leaves to the crock. Besides imparting a bit of flavor, tannins from the leaves firm the cucumbers and keep them crunchy for a long time. White oak leaves (with rounded lobes) are preferable to types (like red) with pointed leaves and much harsher tannins. I use a mixture of white oak, grape, and black currant since I have all three in my yard and garden. It only takes a few; for my two-gallon crock I use a couple of each. (Recipe here.)It’s only worth making these in season with home-grown or locally grown produce, preferably organic. Use small, firm pickling cucumbers; when they get big the seedy, pulpy insides expand and become spongy. They will last you deep into winter, depending on how many jars you put up. Sliced on a burger, accompanying a pastrami on rye, or chopped up in some homemade tartar sauce, there’s almost nothing these don’t make better. It’s important to keep traditions alive, and harnessing the power of microbes to transform and preserve the harvest ranks among the most ancient and valuable culinary practices.