Whether you make yours sweet and sticky with dried fruits — Sephardi style — or the more Eastern European version, packed with cinnamon, nuts and juicy apples, charoset is a Seder night highlight.

By the time we’re dipping our maror in and heaping spoonfuls onto crunchy matzah, the end of the service is in sight and the children are raring to race off and hunt the Afikomen.

And as a nostalgia trigger, it’s up there in the top ten or 20 Jewish foods. Each mouthful evokes memories of past Seders. Impressive for a food invented by Jews to mimic cement.

But according to Jerusalem-based historian Dr Susan Weingarten, had it not been for the Romans we may never have enjoyed this traditional treat. Weingarten reveals in Haroset, A Taste of Jewish History that the fruit-based paste was not originally a part of our Seder service.

“The Torah contains rules about Seder and what you must eat. It talks about the Paschal lamb, maror and matzah but it doesn’t include charoset.”

Weingarten explains charoset doesn’t get a mention for several hundred years, when it appears in the Mishnah’s list of traditions many years later — in the third century CE.

Weingarten has pored over religious texts, archive materials and the only surviving Greco-Roman cookery book to discover the when, what and how of this tasty dip.

What she discovered was that it was almost certainly a food eaten by ordinary people, maybe even an everyday food at one time. Charoset was the Hebrew name of a Greco-Roman food called embamma — mentioned in that Greco-Roman cookbook, which contains a recipe for it and a note that it was recommended as  dip for lettuce and endives ‘to stop them harming you.’

“The lettuce they ate at that time was very bitter — like maror — and they believed that bitter flavours were bad for you. Dipping the maror into the sweet puree would stop the kappa harming you.” It is not entirely clear what kappa is, but it is referred to in the Babylonian Talmud and in several rabbinical texts.

So how did charoset end up on our Seder plate? “I reckon that what happened was that ever since leaving Egypt, the Jews had been eating their maror and parsley. The Romans arrived and said ‘you need to dip it into this charoset to stop them harming you’. So it became part of the service, and the rabbi’s retrospectively added it into the Seder, giving several reasons for it being there, ranging from it representing the blood shed by the Jews to the clay used to build.”

Weingarten believes that at the time it was probably a food eaten all the time and not just at Seder nights.

She explains that where one finds several reasons for something’s existence in religious ritual, it tends to indicate it being a later addition. “The rabbis needed to justify the new ingredients.”

The recipe was also very different in its early days. “It contained dates and a peculiar combination of spices” says Weingarten. “Cumin, pepper and rue, which is a favourite spice of the ancient Greco-Roman cookery book with a very bitter flavour. Other recipes since then also include cumin, pepper and ginger.”

As the tradition travelled around the world, it began to morph to the many variations that we now have — like much Jewish food has done. “In Babylonia in the 10th century, one of the rabbis  — Rabbi Ge’onim — wrote that ‘charoset was made from dates in our part of the world’. Sephardi charoset is still date-based, but it didn’t always have the straightforwardly sweet flavor we now know.

“It was originally made with vinegar, giving it a sweet and sour flavor. The Talmud talks about it being sour. Another well-known rabbi — Rabbi Rashi made his with wine and gave it a name which means sour — aigros — as in vinaigre.”

Whether it represents blood or bricks, the latter has played a big part in Seder ceremonies over the years. In the 16th century, some German Jews shaped their charoset into the shape of a brick, and in 1862, Jewish soldiers fighting in the American Civil War, had no ingredients to make it and so, when celebrating their Seder, used an actual brick instead on the Seder plate.

The brick theme continues with one of the most surprising ingredients, still used by some modern day charoset makers — ground up pottery. “There’s a marvellous case where Rabbi Menahem writes (in the 18th century) about people putting grit in their charoset.  He thinks that people misunderstood or that there was a mistake so the words to grind up your charoset read to grind up a piece of pottery to put in their charoset!”

She explains that it was an odd custom that has surprisingly endured the test of time.

“I interviewed a man called Menachem Parienti, whose family came from Lisbon to Israel, who still do it” says Weingarten. “He even has a Haggadah (published in London in 1813) that said to put a little bit of pottery into the charoset.”

She includes a chapter of recipes at the end of the book and did taste a few versions as part of her research. “One Pesach I went to visit people in their kitchens and we photographed them making theirs. One Yemenite couple made theirs in their garage as their house was still full of chometz.”

What recipe does she use for her Seder? “I have always used my mother’s recipe which was her mother’s, but for the last few years my daughter has made the charoset as she now hosts the Seder meal.

“Our recipe did evolve a little — one year I added too much wine and could only find coconut to absorb it, so now I add some coconut to ours if I have any over from making my coconut pyramids.”

Haroset, A taste of Jewish history by Susan Weingarten, is published by The Toby Press