“We always followed the Ashkenazi tradition,” said Rachel Ringler, 64, a food writer and challah-baking instructor, who will be hosting her Seder over Zoom from Bridgehampton, N.Y., instead of with 30 people in her Manhattan apartment. “We never had rice. We never had lentils. We never even served string beans.”

But she has a son-in-law who is half-Syrian, so she follows different Passover customs.

“I said, ‘We are all Syrian this year,’ ” she said, laughing. “We are stocked with lentils, and so we are going to use those lentils for Passover.”

The Rabbinical Assembly, the international association of Conservative rabbis, has sanctioned eating kitniyot during Passover since 2015. The custom is widespread among Sephardic and Mizrahi Jews with ancestors from Spain, North Africa and the Middle East. In Israel, many follow suit.

This year, the assembly’s Committee on Jewish Law and Standards also offered alternatives for traditional foods on a Seder plate: a roasted beet and rice in place of a shank bone and egg, and any vegetable or fruit “that can bring a tear to the eye” if horseradish isn’t available.

The substitutions won’t be the only thing different on the first night of Passover, which is usually celebrated with a large communal meal with family and friends. Some families who cannot be in the same house plan to cook from the same recipes, as if they were together.

Self-isolating in various homes across the country, some observant Jews might need to embrace technology — normally a no-no — so they can celebrate together. (In Israel, which tightened travel restrictions specifically around the holiday, some are gathering before sundown to celebrate together via Skype or Zoom.)

“We’ve seen rabbis across the board — but especially in the Orthodox community — lowering the bar for Passover,” said Mishael Zion, an Orthodox rabbi who with his father, Noam, wrote “A Night to Remember,” the popular modern version of the Haggadah, the text that guides the Seder. This year, he said, “it’s like the matzo, which is just the basics of bread, water and flour.”