WHILE JEWS all over the world are gathering in synagogues Sept. 8 to commemorate Rosh Hashanah, the Jewish New Year, Jews in the Greek town of Ioannina will be struggling to bring together enough participants to hold a proper religious service.

Before World War II, Ioannina (pronounced Ya'hnina) was home to more than 2,000 Romaniote Jews and two synagogues. Neither Sephardic (of Spanish origin) nor Ashkenazic (of Eastern European origin), these Greek-speaking Jews trace their history directly to the days of the Byzantine Empire.

In March 1944, most of Ioannina's Jews were taken from their homes in the mountains of west central Greece, 200 miles northwest of Athens, to Auschwitz. Only 165 survived the Holocaust, only 70 make their homes in the small provincial capital today, and one of the synagogues was destroyed by the Nazis during the war.

For these reasons, the celebration of the Jewish high holy days--Rosh Hashanah, followed by Yom Kippur (The Day of Atonement) 10 days later--lives on more vividly in memory than in contemporary Ioannina.

Rachel Dalvin, who was born in Ioannina and left shortly after the turn of the century at age 5, now lives in New York City. A former professor who has translated three volumes of Greek poetry, including "The Complete Poems of Cavafy," she has spent the last decade researching the history and traditions of the Ioannina Jews for a book she is seeking to have published called "A Lost Jewish Community." Simultaneously, many of the artifacts of Ioannina Jewry have been gathered for cataloguing and storage by Nicos Stavroulakis, director of the Jewish Museum in Athens. (Information in the museum's activities may be requested from the American Friends of the Jewish Museum of Greece, P.O. Box 1162, Oak Brook, Ill. 60521.)

"In Ioannina," explains Dalvin, "the customary dessert on the eve of Rosh Hashanah was koliva, a thick porridge of wheat berries flavored with cloves, cinnamon and walnuts. It was always sweetened with honey to ensure sweetness of life in the year ahead, and the wheat berries, which expanded during the cooking, symbolized the growth and sustenance of life."

"We also always ate kaltsounakia on Rosh Hashanah," she continued. These are little half-moon-shaped cakes stuffed with ground walnuts, honey and cinnamon and cloves."

Dalvin says the Turkish influence on Ioannina kitchens was profound since the Turks occupied that part of Greece for centuries before the town was conquered by Greek armies during the Balkan wars of 1912-13. On Rosh Hashanah, the women would prepare a variety of dishes common in Turkish cookery, including tomatoes, squash and vine leaves stuffed with chopped lamb, rice and parsley. Another favorite was okra stewed with chicken.

"But Yom Kippur was the most interesting holiday in Ioannina," says Dalvin. "On the preceding day, the children would go from home to home gathering flowers to decorate their large candles. At noon that day, they would march in a colorful procession to the synagogue."

"On Yom Kippur morning, the women of Ioannina would greet each other with the words 'megali mera', meaning 'great day,' Once in the synagogue, they chanted special hymns in the Judeo-Greek dialect unique to Ioannina."

During the high holy days between Rosh Hashanah, which begins at sundown Sept. 7, and Yom Kippur, Jews of Ioannina joined Jews all over the world in asking forgiveness for any injustices committed during the year. Then, when the sun set on Yom Kippur, bringing to a close the most holy day on the Jewish calendar, the Jews of Ioannina broke their 24-hour fast with avgolemono (egg-lemon) soup and a variety of stuffed vegetables. For dessert they always ate something sweet, a symbolic gesture of hope for sweetness in the year to come. SOUPA AVGOLEMONO (Egg-lemon soup) (6 servings)

Ideally this soup should be prepared shortly before serving so the rice will not get soggy and the lemon will not lose its fresh edge. 6 cups rich chicken stock 1/4 cup long-grain white rice 3 large eggs, separated, at room temperature 1/4 cup freshly squeezed lemon juice Salt to taste

In a soup pot, bring the chicken stock to the boil. Add the rice, cover the pot, and cook over medium heat until the rice is just tender, about 15 minutes. Remove the pot from the heat, leave it uncovered, and spoon out about 1 cup of the liquid.

Beat the egg whites to soft peaks. While continuing to beat, add the yolks and beat for about 2 minutes. Then slowly add the lemon juice and then the 1 cup of stock, beating all the while.

Whisk this mixture into the soup until well blended. Add salt to taste. Heat (but do not boil!) the soup over a low flame, stirring constantly, before serving. DOMETES YIEMISTES (Stuffed Tomatoes) (4 servings) 4 very large ripe tomatoes (about 2 3/4 pounds) 1/3 cup finely chopped onion 2 tablespoons olive oil 6 ounces ground lean beef or lamb Salt and freshly ground pepper to taste 1/3 cup finely minced parsley 3 tablespoons rice, soaked for 10 minutes in boiling water and drained scant 1/4 teaspoon sugar

Wash the tomatoes and carefully core them. Cut a thin lid off the stem ends and reserve the lids. Using a teaspoon, scoop out most of the pulp, creating a small bowl with firm walls. Finely chop the pulp and set it aside.

In a saucepan about 3 inches high and 12 inches in diameter, saute' the onions in 1 1/2 tablespoons of the oil until soft. Add the meat and stir over medium heat until it is browned, about 2 to 3 minutes. Reseve 1/2 cup of the chopped tomato pulp and add the rest to the meat, together with the salt, pepper, parsley and rice. Stir in 1/4 cup of water, cover the pot, and simmer the mixture for 10 minutes. Adjust the seasonings.

Meanwhile sprinkle a little sugar in each tomato. Lifting portions of the meat mixture with a slotted spoon, fill each tomato almost to the top and set the lid in place. Stir the reserved tomato pulp into whatever liquid remains in the saucepan, adding a little water if needed to measure about 1/2 inch of liquid in the pan. Set the stuffed tomatoes in the pan, cover, and simmer over medium heat until the tomatoes are cooked throughout, if necessary, 20 minutes. Baste after 10 minutes, adding a little more water if necessary.

If desired, the remaining 1/2 tablespoon of olive oil may be brushed on top of the tomatoes before placing them under the broiler a few minutes to brown. KOLIVA (Wheat Berry Dessert) (4 to 6 servings)

By American standards, this hearty, chewy dish would be more suitable for breakfast than for dessert. Either way, it is satisfying, healthful and delicious. 1 cup wheat berries (available in health food stores) 1/4 teaspoon salt 1/8 teaspoon cloves 1/4 teaspoon cinnamon 2 to 4 tablespoons honey 1 cup coarsely chopped walnuts

In a large soup pot, soak the wheat berries overnight in 2 cups of water. The next morning, add another cup of water and the salt. Bring to the boil, cover and simmer over low heat until the berries burst completely open, about 2 hours. (It is unlikely that you will need to add more water, but check after the first hour and then again a half hour later.) Drain the berries, disgarding any cooking liquid, and stir in the spices and honey to taste. Add the walnuts. Serve in small bowls while still warm.