Open Monday through Friday 11 a.m. to 3 p.m. and 6 to 10 p.m. p.m.; Saturday 6 to 11 p.m.; Sunday 11 a.m. to 4 p.m. and 6 to 9 p.m. All major credit cards. Reservations. Main courses at dinner average $7 to $9. Full dinner with wine, tax and tip averages $15 to $20 a person.

Ethnic restaurants are like perfumes; they distill the sensory core of a culture, having filtered out distractions like politics, economics and ideology. In a Persian restaurant, revolution is irrelevant. No wine is flushed down any drains. The only sides one needs to take are whether one prefers rice with or without dill and lima beans.

Omar Khayyam is a small Persian world filled with music and art, where you are being observed only to see whether your water glass needs a refill. It is a restaurant where my friend from Iran drifted into nostalgia over powdered sumac, and companions who had never been to Iran put caviar into a new perspective that included grape leaves stuffed with split peas and rice in its culinary field.

Behind an entrance so modest you might miss it, Omary Khayyam stretches up three floors, each of which deserves examination. The first floor is a lounge with low, armless chairs reminiscent of cushions, set for conversation or backgammon -- with boards to complete the setting. On the walls are aged etchings of Persian women at work. An old man smokes opium discreetly in the corner, so realistic that if he were full size you might not guess he was wax. The rear of the room is a curved mirror, furthering the unwordly vision that is this restaurant. On the second and third floors are small dining rooms, both of them edged in the ornate wood of the staircase and focused on the bar area where the three-piece band plays and the belly dancer undulates. When the main entertainment has not yet revved up, a pianist plays soft Persian music to reinforce the soft glow of backlit arched windows and skylight, the soft architectural curlicues that delicately define the setting as Persian. Even the shadows become decorative features. The restaurant looks simultaneously modern and traditional. And except for the small tables and nondescript table settings, each facet of Omar Khayyam contributes to its dazzle.

Dressed in black tie, the waiters are initially formal. But as the evening progresses, they relax that pose, becoming friendly tour guides easing you from appetizer to dessert with hardly a hitch.

The first stop is bread, washboard shaped slabs that are light and yeasty, considerably more flavorful than the similar breads at Bamiyan and Khyber Pass. Several dishes will remind you of those two Afghan restaurants, particularly the eggplant with yogurt, mint and garlic. This dish is available as appetizer and main course ( $2 and $6.25, respectively) with slight variations, and its interplay of cinnamon sweetness, yogurt tartness, hot pepper and mint pungency makes a good introduction to the exotic combinations to come. No matter how many times you have tasted stuffed grape leaves, those at Omar Khayyam will be an experience; filled with split peas, saffron, rice and meat, they are intriguingly sweet and lemony. Other Persian appetizers are yogurt with chopped cucumbers, walnuts and mint -- refreshing, delicious -- and spinach with yogurt, on one occasion sharply peppered, the second time bland. And there is caviar, lavishly presented and lavishly priced at $18.50. Soups and salads are fresh and lively, but the main focus should be appetizers -- the best of which are $2 or less -- and main dishes.

Distinctions between shirin polo and baghali polo may be difficult for the uninitiated to anticipate. But despite the long list of main dishes -- 14 of them -- they break into easy categories. Most numerous are skewered grilled meats: chicken, lamb, beef cubed or ground. Choose one, any one. They are marinated in yogurt and subtle herbs, then charcoal broiled so they are smoky and crusty, their insides still juicy, usually rare. While the ground lamb version was least interesting, one might want to try it combined with a skewer of lamb kebab. It is not on the menu, but is called sultanee, this very typical Persian combination plate served with a raw egg yolk to mix into your rice and a side dish of spicy-tart ground sumac to sprinkle over your food. Another form of charcoaled meat here is lamb chops, three of them seared and seasoned with cumin and sumac so they are tangy and faintly tart. Not to be missed. They come with plain, buttery rice and vapid green beans as barreh kebab, or with an intriguing rice heavily dosed with dill and lima beans, called baghali polo on the menu and described as "Persian style rice prepared with lima beans and dill weed served with lamb." Typically Persian, said a friend who should know, to feature the rice and consider the three lamb chops as an afterthought. Two other main dishes need to be mentioned. Khoresht fesenjon is boned chicken hidden under a fascinating sauce of pomegranate juice and nuts, nutty and rich and slightly sweet. It is easy to understand why it is a Persian favorite, so popular that the grapevine is circulating a recipe substituting grape juice and sweet potatoes for Persians stuck without a supply of pomegranate juice. The other Persian favorite -- and our waiter's favorite -- was the one dish I found that no diner I encountered has liked. Shirin polo is grilled chicken served dessert-sweet, in a sauce like diluted orange marmalade. Remember the warning. And remember not to expect much from the vegetable accompaniments.

In the unlikely case you are still hungry, there are some creamy, liqueur-drenched cakes layered with fresh orange or sometimes raspberries. They are quite good. Baklava is admirably flavored with walnuts, sesame and cardamom, but it tends to be either soggy or floury. The fitting ending -- though an expensive one at $4 a person -- is Omar Khayyam Coffee flamed at the table (for a minimum of two people). It is the flourish that counts, the flaming of a spiral of orange peel and varied blazings and swirlings that culminate in a very boozy brew. Like the restaurant itself, a grand show.