Until they opened Mesob in November, Berekti and Akberet Mengistu had never even worked in a restaurant. But having grown up in a family of 10 children, the Ethiopian sisters have plenty of experience cooking for a crowd, which is what they hope to attract when Mesob holds its grand opening tomorrow through Sunday.

Ethiopian cooking is all about family-style eating. Most of the dishes are rich, thick stews, long-simmered and served on spongy sourdough crepes that double as plates and, when torn into pieces, even as spoons. Scoop it up with fingers and a piece of the crepe, called injera, and you have an Ethiopian meal.

At their home in East Brunswick, the sisters are familiar with people dropping in for dinner. Two of their seven brothers live nearby, and a third brother lives in Manhattan. They have more than 100 cousins on their father’s side alone.

“People are always visiting, coming for weddings, staying with us,” says Berekti. Dinner for eight is a minimum. Dinner for 30 or 40 is no big deal.

At Mesob, which is located at 515 Bloomfield Ave., Berekti is the manager and Akberet the chef. They began to think about a partnership four years ago, after Akberet, who had been running their late father’s hotel and trucking business in Addis Ababa, came to live with Berekti, who ran software development projects for AT&T and Lucent. The girls had been trained in Ethiopian cooking by their mother, whose 1997 funeral was the last occasion when all 10 children gathered at one time and place.

Since East Brunswick already had an Ethiopian restaurant, the Mengistus looked elsewhere. Inevitably, the project became a family affair. Their cousin Amanuel Michael, a real estate agent in West Orange and Montclair, found the space, which had previously been a seafood grill, an Egyptian restaurant and, back when, a health food store. Michael’s wife, Azeb, an architect, handled the permitting. The firstborn, Daniel, who lives in Plainfield, backed the venture financially. Berekti’s friend, the New York bridal gown designer Manalé, who is Ethiopian, chose the palette of earth tones for the awning, menu and interior.

Mesob, which is pronounced with a short e and a long o, is named for the round wicker tables, with their decorative dome-like covers, at which Ethiopian families traditionally dined. Patrons can sit at mesobs near the front windows, or at regular tables. Wherever they sit, they will hear recorded Ethiopian pop music, improvisational and rhythmically intricate, playing softly in the background.

On the walls hang works from Berekti’s collection of Ethiopian and Eritrean art, including what appears to be a set of four large fabric sculptures. These turn out to be traditional tribal papooses made from leather and trimmed with seashells from the Red Sea.

“I wanted the restaurant to look like an art gallery,” says Berekti of Mesob’s long, high-ceilinged walls, one of which is brick. “I’ve never seen this art shown the way it should be.”

The most collaborative effort of all produced the most striking result — the seven cylindrical lamps that cast a toasted-wheat glow over the bar that runs down the center of the room.

Each lamp is a tan cylinder four feet tall made of paper-thin leather stretched on a metal frame. The parchment-like leather is covered with rows and columns of burnt-umber-colored characters — the 33 letters of the Amharic alphabet, each of which has seven vowel-sound variations, and a table of Amharic numerals.

“My brother in the Netherlands, Amanuel, designed the lamps, and my brother Henok, who lives in East Brunswick, assembled them,” says Berekti. One of the lamps, instead of the alphabet, is painted with scenes of life among Ethiopia’s Afar tribe.

“This is all a family’s love,” says Berekti, standing at the bar, gesturing around the restaurant.

Spiced tea and strong coffee are prized in Ethiopia, and the bar will feature both. Mesob grinds spices for the tea daily. The flavors include cinnamon, ginger, cardamom and cloves in a black-tea base. The bar will feature a half-dozen different teas, along with American desserts made by Montclair baker Raymond Reid, whose company is called Tart & Soul.

Dessert is admittedly not an Ethiopian dinner’s most inventive hour. Fresh fruit is typical. In drinks, honey is the traditional sweetener. Ethiopians make an aperitif-like honey wine called tej. Children drink berze — water sweetened with honey. “Sugar is not popular, though we grow it,” Berekti says. “It is associated with modern times,” she explains, notably the occupation of Eritrea by Italian forces before World War II.

Ethiopian cooking is powered by a spice paste called berbere, which is made from a paprika-like pepper combined with cayenne, salt, onions, ginger and other spices, and toasted over low heat.

Main courses are slow-cooked, with constant stirring. “It’s like risotto that way,” says Berekti. Meat stews are prepared with clarified butter. “In Ethiopia the cows eat grass, that’s it. There are no hormones and we use a lot of butter,” she says. “Here, we use much less.”

Ethiopia’s population is about equally divided between Moslems and Coptic Christians. Vegetarianism is important in both religions, and meatless dishes contain no butter, eggs or other animal products. About a third of dishes on Mesob’s menu follow this vegan tradition.

The Mengistu family attend a Coptic church in New York City. Their surname may sound familiar: Colonel Mengistu Haile Mariam led the junta that violently deposed Emperor Haile Selassie in 1974. Berekti wants to make one thing perfectly clear: “There was a horrible president, a brutal dictator, by that name, but we are not related to him.”