The cell phone went unanswered.

"We're busy," said Barbara Pope, her hands covered with flour. "We're creating."

Pope was one of 11 women who recently took part in a women-only challah-baking class in San Francisco's Noe Valley, sponsored by Chabad of Noe Valley.

And as the women were to find out, making the golden loaves for the Sabbath table transforms the process — it's a whole lot holier than just baking bread.

Baking challah is one of the three mitzvot required of women in the Jewish tradition, according to Leah Potash — who, with her husband Rabbi Gedalia Potash, set up a Chabad house this past summer. The other two mitzvot: lighting the Sabbath candles and, for married women, going to the mikvah, the ritual bath. (Men can bake challah and light Sabbath candles in the absence of women.)

In class, the dining room table was covered with plastic; atop that sat bags of flour and sugar, bottles of oil and large plastic bowls.

The yeast came first, and Potash got the water just the right temperature. "The temperature has to be right," she said. "Hotter than cold, but not too hot."

If the yeast mixture bubbles, that's OK, she said.

Potash gave a brief explanation of some of the kashrut laws that come into play when making challah. "Both flour and sugar don't need kosher symbols on the bag," she said.

Eggs must be broken in a glass, she said, to closely examine them and ensure there are no blood spots. A blood spot makes an egg non-kosher, and it must be thrown out. In addition, eggs are broken individually into the glass, so as not to spoil the whole mixture if one should be non-kosher.

As the women kneaded, Potash circled the table, a bag of flour in hand, adding a bit more to some of the bakers' bowls. "The dough shouldn't be sticking to your hands," she said.

"I feel like I'm channeling grandma," remarked Betsie Simon, as she kneaded away.

Meanwhile, some of the first-time kneaders discussed the goopiness factor, and compared the feel of it to mud.

Before leaving the dough to rise, Potash instructed the bakers to cover the surface with oil, flipping the dough to get both sides, so it wouldn't stick to the bowl.

Then it was rising time, and the women moved to the living room. First came a discussion of what may and may not be done with challah. Freezing? Yes, but it won't taste as good and may suffer freezer burn. Freezing the dough after it's shaped is fine, and with the proper amount of rising time, you won't be able to tell that it was frozen.

Adding chocolate chips, cinnamon, blueberries, even rosemary and oregano? All OK, although for Sabbath, Potash prefers the plain and simple.

Then, a discussion of the spiritual aspects and the three mitzvot required of women. And the fact that when making more than 3 pounds 11 ounces — derived from an older form of measurement — a small amount of dough must be burnt and a blessing said.

"In the Holy Temple, when bread was made, a small piece of it went to the Kohen," she explained. The practice continues today because "it reminds us that it doesn't all belong to you."

Potash burns the dough by wrapping it in tin foil and placing it at the bottom of the oven. In her preparations for the Sabbath dinner, it will burn automatically.

It also allows us to "remember where it came from," Potash said. "We put God's blessing on everything we do."

Also, challah for Sabbath must never be made with any dairy products, she explained. If you do decide to add milk, you must form it into a different shape, so no one will mistake it for pareve challah and eat it with a meat meal, she said.

Even if a person is alone on Sabbath, she should have two loaves of challah. The reason? Because when the Jews were in the desert after leaving Egypt, and the manna fell from heaven, twice the amount fell on Friday, so they wouldn't have to work to collect it on Sabbath. The two loaves are a reminder of that miracle.

When the dough was ready to be shaped, some women fashioned the traditional three-strand braid, while Potash demonstrated how to make a loaf with four strands. One can also do a six-strand braid, but Potash herself has never mastered it. She passed out a diagram, and some of the women tried to do it.

After the challahs were shaped, the women offered their assessments before taking them home to let them rise again, and then bake or freeze them, depending.

"They look like little chickens," said Martine Klinman.

Jenny Traig gave half of hers away; she came to the class even though she is on the Atkins diet, which pretty much bans carbohydrates. So why did she come? "I've always wanted to learn how to bake challah."