Note how I say "sabbath" instead of "shabbes" in a cheap attempt to attract non-Jewish readers. Here' a little bit about tsholnt, sometimes spelt cholent and often pronounced tshoolnt, from my still-to-be-published book on Yiddish food, Rhapsody in Shmaltz:
Cholent is the ground zero–the big bang, if you ask those who eat it–of east European Jewish food, the primal ooze from which many of the best-known, most characteristic Yiddish dishes emerged. While most of the traditional dishes that we eat today started out as shabbes or holiday foods, those holidays come but once a year; shabbes takes place every week. The kugel, the heldzl, the kishka, all came out of cholent; the tsimmes and ptche were its intimate associates. As the mother, father, and native land of Sabbath-oriented food preparation, cholent has been shaping tastes and eating habits for centuries. It is second only to matzoh in age and, with the possible exception of matzoh, is the only Jewish food that might have originated with the Jews themselves. Matzoh balls owe their existence to a German and Slavic fondness for dumplings; all we needed for cholent were God, a couple of apparently contradictory commandments, and a healthy appetite for doing things aftselakhis, just to piss people off. Cholent starts out as the slow-cooked counterpart of a gay wedding held in front of an Orthodox synagogue or Catholic church.
The first thing that it had to do was to reconcile the prohibition against cooking on the Sabbath with the commandment to call the Sabbath a delight. The rabbis of the Talmud–Pharisees, in standard English terms–interpreted the latter as an injunction to eat a hot meal during the daytime on shabbes, in addition to the one on Friday night. This meal wasn't only about food; it was meant as a slap in the face to the Sadducees, the Pharisees' main rivals for power within the Jewish community, who rejected any number of the Pharisaic doctrines and beliefs that have come to define Judaism as we understand it; indeed, they rejected the whole notion of an Oral Law that complements the written Torah. Very much oriented toward the Temple in Jerusalem–the New Testament Book of Acts tells us that "The high priest rose up, and all they that were with him (which is the sect of the Sadducees)" (Acts 5:17)–Sadducees tended to a more linear, literal-minded reading of the Torah than the Pharisees.
The two factions disagreed over the interpretation of Exodus 35:3. The standard translation–"Do not kindle a fire in any of your settlements on the Sabbath"– reflects the Pharisaic reading, but Hebrew grammar can always provide a fertile field for disagreement, especially when there might be nothing else to argue about. The Pharisees took the verse to mean "Do not cause a fire to burn," that is, making new fires was forbidden, but benefitting from old ones, within carefully prescribed limits, was all right. The Sadducees, on the other hand, read the verb simply as "burn" and took the verse to mean that no fire at all was to be allowed in those settlements. They spent the Sabbath in the dark, eating cold food, and not doing anything else to heat things up: they also forbade sex on shabbes–lest it light their fires–along with leaving the house (unless they were priests on duty in the Temple). For all we know, they banned garlic on shabbes, too.
The Sadducees disappeared soon after the destruction of the Temple. While their influence might never have been as widespread as that of the Pharisees, it seems to have ranged widely enough to contribute to the not uncommon Roman idea of the Sabbath as a fast day. While not accurate even for Sadducees (the Talmud does cite a couple of isolated cases of Pharisaic rabbis–the only kind there was–who found nothing wrong with fasting then), it could very well be based on a mistaken interpretation of the abstention from cooked food.
Some Sadduccean ideas were revived centuries later by the Karaites, a breakaway Jewish sect that accepts the Written Law but not the Talmud or any of the laws or traditions derived from it. Like the Sadducees before them, Karaites ban any use of fire on the Sabbath. Karaism attracted alarming numbers of adherents between the ninth and twelfth centuries, and considerable time, effort, and rabbinic ink were devoted to combating its influence. As late as the mid-fourteenth century, David Abudarham, the Spanish author of a standard commentary on the liturgy, quotes the twelfth-century Provençal sage Zerachya ha-Levi on the importance of eating khamin, hot food: "Anyone who does not eat khamin on the Sabbath should be investigated, lest he be a min [heretic; here, Karaite]; should he die, let him be looked after by amamin [non-Jews]." It's those mins at the end of every word that make this joke funny. Four hundred years later Moses Isserles expresses the same idea, but in an entirely serious context: "Anyone who does not trust the words of the sages and forbids the eating of khamin on the Sabbath is suspected of heresy." A hot lunch on Saturday started out as a protest, a way of defying the Sadducees who controlled the Temple and sought to impose their ideas on the masses whose tithes and offerings had helped to enrich them; in the Middle Ages, it turned into a pledge and outward sign of orthodox practice and belief, an internal Jewish analogue to the role that keeping kosher plays in the outside world. From day one, though, it also provided a definitive solution to an apparently contradictory demand: eat well, but don't dare do any cooking. It is the legacy of the Pharisees