It is evident in the stacks of food processors for sale at The Buzz appliance store, with their special “kugel blades” for making a starchy pudding that does not require bread, or in bakeries that make matzos by hand within an exacting 18 minutes, or in garages equipped with vats of boiling water where Jews immerse cooking pots that might contain chametz. It is also evident in a seasonal uptick in employment, because the neighborhood has no shortage of experts in the finer points of fastidiously keeping kosher who supplement their livelihoods during Passover.

“God in Borough Park is like steel in Bethlehem,” joked Alexander Rapaport, a Hasid who runs Masbia, a soup kitchen organization.

The first item a customer notices when entering Gourmet Glatt, a sparkling new emporium that resembles a Whole Foods, is not food, but a tall stack of Easy-Off. That is because among the first things a Hasidic homemaker does before preparing holiday dishes is clean the oven two or three times to make sure not even a speck of chametz from the past year contaminates those dishes.

Once inside the market there are other signs of how the holiday, known in Hebrew and Yiddish as Pesach, is observed with scrupulous rigorousness. The shelves are lined with brown butcher paper so that Passover products are not exposed to the year-round boards. There are two counters of vegetables — washed and unwashed. Although the Talmudic injunction is a matter of interpretation, many Orthodox families prefer their carrots, beets, radishes and parsnips straight from the soil, with granules of dark earth still clinging. That way they can wash the vegetables themselves and be sure, or as certain as humanly possible, that no grain alcohol or leavened grain byproducts touched them.

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For the same reason, Hasidim will buy only unwaxed apples — the store has such a bin — and eat only gefilte fish made of carp because it can be bought live, assuring its purity.

“On Pesach people don’t want anything chemical, even if it’s not chametz,” said Rabbi Shmuel Teitelbaum, the store’s mashgiach, or kosher monitor.

Hasidim from the Belz sect will not touch garlic during the holiday. Not because garlic is chametz, but because generations ago in Europe garlic was preserved inside sacks of wheat. Since their ancestors did not eat garlic, Belz Hasidim will not eat garlic. Tradition is tradition.

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The other day, Mordechai Rosenberg, a 50-year-old Bobov Hasid wearing an astrakhan fur hat, was pushing a cart loaded with boxes of sugared cereal made from potato starch. He felt compelled to explain to another Hasid that they were for his grandchildren.

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“I eat what my parents taught me,” he said. “I won’t even put jam on my matzo because it could have a little drop of water that will mix with the matzo.”

In some Hasidic ways of thinking, dipping matzo or matzo meal in water may leaven some trace of unseen flour. That is why Hasidim, as opposed to other ultra-Orthodox Jews, will not eat matzo balls with their chicken soup (they use cooked egg instead) and why kosher supermarkets sell more potato starch than matzo meal.

Rabbi Menachem Genack, the rabbinic administrator of the Orthodox Union, which certifies foods in 83 countries, explains that the rules forbidding chametz are more severe than for nonkosher foods like pork. Jewish law tolerates some contamination of kosher food, as long as it does not exceed one-sixtieth of the total consumed; with chametz, even the slightest speck renders a dish inedible.

The frenzy for Passover perfection is palpable inside The Buzz, a kosher cross between a Williams Sonoma and a Best Buy that is especially bustling this time of year. Juicers become a particularly hot item. All year long, ultra-Orthodox Jews drink Tropicana and other processed juices that bear rabbinical certification. On Passover, particularly fussy ones buy juicers to squeeze their own and avoid possible contamination in the manufacturing.

Food processors are also a best seller; The Buzz sells thousands. The most popular, said Heshy Biegeleisen, one of the owners, is a 14-cup machine made by Gourmet Grade that has the “ultimate kugel blade.” It prevents the potato batter from having a soupy consistency associated with some food processors. The blade was designed by engineers in China after Mr. Biegeleisen spent three weeks there figuring out with them how to forge a device that could create the granular texture of a hand grater (minus the blood that often comes with a cut finger). The answer was a blade that alternated large holes with small holes.

For four months ahead of Passover, Charedim Shmurah Matzah Bakery, planted in the shadow of the subway, turns out 80,000 pounds of hand-kneaded, flattened and perforated matzos in an atmosphere of high-wire tension, monitored by timers. Shmurah matzos are “guarded” from the time the grain is harvested and milled until the time the dough is baked, and only 18 minutes can pass between the mixing of the water and flour and the insertion into a very hot oven.

The process echoes the haste of the ancient Hebrews as they rushed to bake bread before escaping from Egypt. Still, at times the bakers carrying long rods loaded with discs of dough and sprinting to get them into the oven recall a less ancient phenomenon — the Olympics. They look like pole-vaulters running down a track as if the gold medal were at stake.