Kosher caterer David Dahan is not what you'd call a placid person. He gestures with his hands and his voice booms, first in English, then French, then back to English. He sits for an interview, but you sense that it's an effort for him to stay tethered to the chair. He'd like to be up, running to the kitchen, tasting things, answering the phone. Yelling.

Oh, yes, he yells. "I'm not the easiest person to work for," he admits with a sheepish laugh. "Just ask my daughter." His 23-year-old daughter, Karin, who helps with the business, just smiles.

Whatever you want to call it -- energy, passion, hardheadedness -- it's worked out well for Dahan. In just six years, his Rockville firm, Dahan of Washington, has established itself as a premier caterer for those who need strictly kosher food that's also strictly gourmet quality.

With the Jewish High Holidays approaching, Dahan's chefs will be preparing meals for Rosh Hashanah, the Jewish New Year, which begins at sundown next Wednesday, and Yom Kippur, the Day of Atonement, which begins at sundown on Sept. 24. Both of these holidays involve full days at the synagogue; on Yom Kippur, many Jews fast during the day and cooking is prohibited.

As an observant Jew, Dahan won't be working on those holidays and neither will his staff. So how will he provide his clients with a festive Rosh Hashanah dinner or a hearty break-the-fast meal on Yom Kippur? More to the point, how will he do it in his own home?

The solution -- for caterers or home cooks -- is a do-ahead menu. Dahan devises French- and Moroccan-inspired dishes that can be prepared a day or two ahead of time, chilled and then served to family and guests at room temperature or with only brief reheating. Some of his favorites include chilled baked salmon drizzled with an easy mayonnaise-based herb sauce, French lentils tossed with vinaigrette, and a colorful Moroccan chicken tagine, or stew, served on a golden bed of saffron rice.

Moroccan food, in particular, lends itself to long cooking and benefits from reheating, says Dahan, who was born 50 years ago in a Moroccan village. "Food for us was the most important part of our life," he says. He was one of nine children and his mother made all their meals from scratch, including the bread. "I never ate a meal in a restaurant until I was 24" and living in France, he says.

He studied hotel and restaurant management in Strasbourg, France, then moved with his wife and young daughter in 1978 to San Francisco, where he eventually opened a restaurant called La Chaumiere. The menu was basically French, but with some of his beloved Moroccan specialties like harira, the hearty soup made with lamb, lentils, chickpeas and pasta that is traditionally served to break the day-long fasts during the Muslim holiday of Ramadan.

In 1987, he sold the restaurant and subsequently was hired as food and beverage director at the posh Stanford Court Hotel. All was fine, he says, until 1989.

"That year, my father died and then that terrible earthquake hit San Francisco. It scared the hell out of me. For two days I was trapped at the hotel, unable to reach my family," he remembers.

The experience convinced him to move. His wife had family in Potomac, so he and his family headed east. His third daughter ( now 13) was born, and for a while he gave up the food business and worked as a stock broker.

But food was too much of a lure. He opened (and closed) a kosher restaurant in Washington, then turned his sights to catering. "Let's face it," he says with his customary bluntness, "kosher food doesn't have the greatest reputation. It's all kugel [noodle pudding] and dry, tough beef."

Dahan was determined to change that impression. He hired young French chefs. He made an effort to use uncommon ingredients such as venison, buffalo, goose liver and pink peppercorns. He aged his own beef and worked with his chefs to come up with substitutions for ingredients normally not allowed under kosher dietary guidelines; for example, he uses beef bacon, instead of pork, to add flavor to lentil salad. His pastry chef makes chocolate ganache with non-dairy creamer so that it can be served at a meal that includes meat (under kosher law, meat cannot be eaten with dairy foods).

The company opened in 1998 with 3,000 square feet of kitchen and office space. Dahan's first event was a wedding for former Bill Clinton staffer Steve Rabinowitz. The business kept growing, and a few years ago, it moved to an 11,000-square-foot space in Rockville. To ensure that his food meets the most stringent of kosher dietary laws, the company is certified by the Vaad Harabanim of Greater Washington, an organization of orthodox rabbis that oversees kosher food preparation. As Dahan's chefs work, a rabbi stays in the kitchen, making sure that dietary laws are followed.

In addition to a heavy schedule of weddings and bar mitzvahs, Dahan has catered a kosher dinner at the White House in honor of the Anne Frank exhibit at the United States Holocaust Memorial Museum, and a lunch at the U.S. Supreme Court. He's done large political party fundraisers and small gatherings for members of Congress, including Democratic Sens. Joe Lieberman and Christopher Dodd of Connecticut.

Although he caters to those who keep strictly kosher, his biggest challenge comes from clients who don't keep kosher themselves, but still need to serve a kosher meal. When they taste his food, Dahan says with a chuckle, "they don't believe that food this good is kosher."

Make-ahead dishes that work for the Jewish High Holidays: Chilled baked salmon drizzled with an herb mayonnaise, above, and Moroccan Chicken Tagine, at right. At upper right: caterer David Dahan, with his executive chef Stephane Mangin and Dahan's daughter Karin in their Rockville kitchens.