Most of San Diego's Vietnamese restaurants are out in City Heights or up in Linda Vista — and most start their names with "Pho," North Vietnam's hearty peasant noodle soup. Nothing wrong with pho, but when a Vietnamese restaurant that emphasizes the sophisticated cuisines of Saigon and Hué opens in the heart of Hillcrest, it's news.

Owner Patrick Hong Luu designed his Saigon on Fifth as a serenely elegant spot. (It's no relation to the funky Saigon on El Cajon.) A curvy yellow couch flanks the doorway; a large white Buddha fountain greets entering diners. The airy room is furnished with cherrywood tables with white tablecloths, chairs upholstered in red damask, and comfortable booths for four along the walls. The waiters wear black uniforms, while the impossibly slim waitresses are clad in gold satin ao dai, Mandarin-collared side-slit tunics worn over narrow pants.

Formerly a Rubio's, the menu at 3900 Fifth Avenue has gone from tacos to tamarind. Now the menu begins with soups, salads, and appetizers and includes the usual list of "classic entrées," where you choose your protein (tofu, mock-chicken, real chicken, meats, or seafoods) and a garnish (red curry, yellow curry, lemongrass, etc.). What sets the restaurant apart from the typical low-rent Vietnamese restaurant is a separate list of house specialties, including many entrées you won't find elsewhere in San Diego. Best to concentrate on this section of the menu.

A tamarind soup at our first visit sold us on the restaurant. It revealed an exquisite balance of sweetness and faint tartness, with soft and crunchy textures. In the clear, red-brown broth floated crisp raw bean sprouts, pineapple wedges, tomato chunks, firm slimeless okra, spongy Vietnamese celery (which slurps up the broth's flavors), and a few "watch out!" slices of Serrano chile -- plus plenty of sharp, licorice-flavored Asian basil. We chose shrimp for our main ingredient (other choices are vegetables and tofu, fish, calamari, and chicken), and they were large, tender, and flavorful.

On a return visit with our friends Sam and Keith, we ordered the excellent "signature" crab and asparagus soup. A complex broth is thickened with a flick of cornstarch and topped with a raft of white pepper to stir in. Sam didn't notice it and was bitten at first bite: "Whoa!" he said. "This is certainly peppery!" Short lengths of white asparagus are mushy but pleasing, mingling with clumps of crabmeat that are clearly freshly pulled from a fresh crab. A flotilla of powerful cilantro leaves and chopped chives brings the flavors to life.

Our favorite appetizer here, spiced baby clams, features unexpected flavors from Hué (a.k.a. "the Forbidden City"), the old royal capital in the center of the country. The chopped tiny clams were sautéed with a chili-garlic-mint sauce that came off more sweet than pungent, courtesy of caramelized onions. It had an intriguing salty, funky undertone from nuoc mam (rhymes with "Look, Mom!"), Vietnamese fish sauce. "This would be perfect if they cut the sweetness by about two-thirds," said Keith. I learned later from the owner that honey is used instead of sugar for sweetness here -- and it's sweeter. The mixture was served on large triangular lobster crackers (similar to the more common Indonesian shrimp crackers) -- porous and brittle, with their own sugary undertones.

Sugarcane shrimp is also from Hué, a onetime palace dish. The kitchen does a good job with the texture -- the shrimp mixture is soft, not rubbery -- but it's underseasoned. It comes with a sweet nuoc cham, a light, chili-flecked red dipping sauce based on nuoc mam. (You can't really taste the fermented anchovies.) Missing was the customary pile of leaf lettuce, mint, and basil to wrap the shrimp in. We found the dish a tad drab without these authentic flavors and textures for contrast.

Also disappointing were fresh spring rolls, filled with flavorless overboiled shrimp and pork slices, plus a mass of vermicelli noodles surrounded by romaine and mint leaves strong enough to unbalance the overall flavor. "Guess we should have chosen the fried Imperial Rolls instead," said Sam. "At least those have a seafood stuffing." Green papaya salad in chili tamarind dressing with a chopped-peanut topping is bland as well, especially if your mouth is set for the spicy Thai rendition. An alternate version that wasn't available that evening centers on baked, seasoned Vietnamese beef jerky in a ginger-and-soy dressing -- worth a try for the unusual meat. We did enjoy the sautéed crystal dumplings, classic rice flour dim sum wraps filled with chopped shrimps, bay scallops, and jicama. (Jicama makes a perfect substitute for fresh water chestnuts when the latter are unavailable.)

Happily, most of the specialty entrées here surpass the hit-and-miss starters. A colonial-era Viet-French smoked-oyster omelet offers juicy, creamy, smoky oysters (canned or packaged, but good) in a well-browned, fluffy omelet stuffed with ground pork, onions, vermicelli, and dried mushrooms -- along with the bivalves. It comes with a thick red dip that looks like American cocktail sauce but is instead spicy-sweet-sour. A smear of this lively mixture is vital to the dish's overall impact.

360û beef is the delicious house version of Shaking beef, a favorite dish at Vietnamese restaurants in America. Squares of tender filet mignon are first grilled, taking on a smoky flavor, then mixed with a wokful of black pepper, garlic, caramelized onions, plus red and green bell pepper strips and carrot sticks. It's a highly satisfying dish.

I've never encountered anything like Saigon's coconut shrimp before, but it certainly tastes like a royal dish. (It's actually a creation of the owner's mother, who's the executive chef here.) A whole young coconut with a hinged lid arrives at the table. Baked inside are plump shrimp, first fried in a millimeter-thin tempura batter and set to floating in a slowly thickened sauce of fresh coconut juice, honey, and lime leaves. It's like shrimp candy -- not cloying but devilishly decadent. Order this when you have friends to share it with -- a little goes a long way.

Saigon Love Boat is also designed for sharing. It's a seafood combination served in a glazed ceramic boat-shaped dish with a craning bird for a figurehead. Inside are shrimp, mussels, dried calamari (looking like baby corncobs), and tilapia, all wrapped inside banana leaves, then rewrapped in aluminum foil. The double "papillotes" keep the seafood tender in the oven. The sauce is pleasantly fishy, seasoned with Kaffir lime leaf and herbs. It took a bit of work to detect all the morsels in the dark sauce surrounded by layers of insulation -- the waitress helped us find the last of them before she cleared the plate: "There's a mussel -- you don't see it? And a shrimp here!"

"Fish of Hué is one of our most popular dishes," said the handsome waiter who served us at our first dinner. You have a choice between sea bass and salmon (we chose bass) that's been marinated in garlic, ginger, and lemon grass, then battered and pan-fried with red and green peppers and white onion in a light, sweet sauce. Popular, perhaps, but we didn't find it especially exciting.

Carrying the theme of sweetness to its ultimate, Tamarind Crab consists of a whole crab in its shell sautéed in a thick, sticky sauce of tamarind and honey, then chopped into large pieces for serving. Some pieces were overcooked, most were just right, but the sauce tastes like the standard universal rendition, whether you're eating in Hong Kong, Lampong, or Haiphong. "Every time I order this dish," said my partner, "I end up telling myself, 'I shoulda gotten the garlic crab (or the chili crab, or the black bean crab) instead.' Next time, remind me to order something else." It's also messy eating -- between the weighty sweetness and the sticky fingers, none of us managed to consume very much.

Bun -- spicy noodle salad -- is indeed a boon, a welcome palate-clearer after the crab, and also a perfect light dish to start a meal. (You'll find it listed on the last page of the menu, like an afterthought.) You get a pile of thin white rice vermicelli plus your protein of choice, surrounded by piles of mint, basil, bean sprouts, cucumber sticks, and tomato quarters. You toss it like a salad as best you can and dress it from a separate bowl of nuoc cham, the sweet-spicy light-red chili sauce. With its clean, healthy flavors, this seems more typical of classic Vietnamese cuisine than the heavily sweetened dishes here.

The theme that runs through the menu is honey, often combined with tamarind into a tropical sweet-sour. This is not a major flaw, but the sameness grows annoying. While most Vietnamese restaurants lack so pronounced a sweet tooth, these dishes aren't adapted so much to American tastes, says the owner, as to the tastes of the French colonials.

The restaurant offers just two desserts: coconut-fried banana and Vietnamese-French "flan" (crème caramel). We passed. Not only were we full, but we'd had our share of sweetness for an evening. Yet we were also content. The only other local Vietnamese restaurant that I know of to serve the cosmopolitan French-influenced dishes of South Vietnam is Le Bambou in Del Mar. At Saigon on Fifth, you can enjoy a distinctive version of this cuisine without a fraught passage through the I-5 "Merge of Death." As the Governator used to say, "I'll be back."

ABOUT THE OWNERS

Saigon-born Richard Hong Luu comes from a Vietnamese restaurant family. "My uncle owned a restaurant in Saigon that only the upper class could afford -- royalty, ambassadors, corporate businessmen. The food was a combination of Vietnamese and French, from the colonial era in the country. He had to charge a lot -- $20 per dish! -- because the food took a lot of labor and good ingredients."

Luu's mother is Vietnamese, his father is Chinese. "We've always had Chinese restaurants, but my mother wanted to do a Vietnamese restaurant -- more fresh." In San Diego, he's been operating restaurants for 20 years, including Taste of Szechwan and Thai Cafe in Kearny Mesa. "My mom used to cook for one of the royal families in Vietnam. Many of the dishes we do are royal dishes. She used to cook here almost full time, but now she's cut back to a few hours a week. She's always cooked for lots of people. Now she's thinking of teaching cooking and writing a Vietnamese cookbook to expose more people to our authentic flavors -- not the simple flavors, but the dishes from the colonial era, when the food became a combination of Vietnamese and French."