The starters are delectable, but the main courses falter at Singers’ Aliso Viejo spot. : A Loss of Momentum at Opah

Settling into a heavily padded patio chair at Opah in Aliso Viejo, a dinner companion looked around and said in surprise: “I thought this was going to be a Greek restaurant.�

The name “Opah� does indeed suggest the traditional exclamation made when Greeks dance or smash plates when they’re in a party mood. It also is the name of a dark-fleshed ocean fish also known as the moonfish, which in Hawaii is said to bring good luck to fishermen. This restaurant is named after the fish, and it is now Aliso Town Center’s most accomplished eatery.

Opah is the latest restaurant designed by architect Mark Singer and his Peruvian-born wife, Miriam. The Singers are the same team responsible for the stylish and popular 230 Forest Avenue in Laguna Beach.

I relayed this information to my friend, who hails from Laguna; he perked up considerably. “Why didn’t you tell me this was Mark Singer’s new place?� he said with a grin. “I would have skipped lunch.�

That would have been a good idea, since the portions at this eclectic new restaurant are huge. Your faux-parchment napkin holder unfurls into an attractive menu. The restaurant’s logo is printed on one side, the dishes are listed on the other.

Opah’s design is casual and fun. The main dining area is illuminated by diaphanous fin-shaped chandeliers. Three giant wall-mounted mirrors add light and the illusion of space. The tables are placed uncomfortably close to one another, but their unvarnished wooden surfaces are strikingly handsome. This isn’t exactly a comfortable restaurant, but it is a slick one.

Our dinner on the patio went well because we arrived at 5 p.m., before things started to heat up. Any time after 6, though, expect noise, crowds and South County’s liveliest bar scene. After working hours, hordes of beautifully dressed young men and women come to wrap themselves around designer martinis and Opah’s sky blue glass-topped bar.

In fact, when we arrived after 7 another evening, we were herded into a table set just behind the bar, our view of the main dining room completely blocked. When our waitress finally arrived after an unreasonably long delay, she apologized, informing us that she had been upstairs “ironing her shirt.�

Happily, Opah’s best dishes are well worth the wait. The Florida stone crab cakes are crisp on the outside and full of flaky crab meat. Next time I order this dish, I’ll ask the kitchen not to sprinkle the cakes with balsamic syrup, though. The syrup itself is fine, but on crab cakes with this kind of purity, it’s a sticky distraction.

The Louisiana oyster po’ boy also makes a great starter, although it’s intended as a main dish. It’s a baguette smeared with tomato tartare and filled with plump, juicy Puget Sound oysters that have been lightly dredged in cornmeal and deep fried. The po’ boy works for sharing because it is really too bulky to pick up and eat like a sandwich. Don’t act surprised if you discover that you and your companions fight for the last oyster.

From the menu’s steamer pot section come delicious Prince Edward Island mussels in a mild, pleasant roasted tomato reduction. A pail of messy, hard-to-stop-eating peel-and-eat shrimp comes to the table steamed in a combination of beer and the pungent Old Bay seasoning that Marylanders use to season blue crab.

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I like Opah’s salads too. A good Oriental chopped chicken salad is laced with a restrained sesame ginger dressing, drizzled with an unctuous rice wine peanut sauce and enriched with chunks of white meat chicken. The house Caesar has tasty Reggiano Parmesan croutons. And a California take on salade Nicoise uses steamed potatoes, French beans and kalamata olives to complement a tall hunk of blackened ahi.

I would have come away much happier had I not been obliged to taste the main courses. Here, the kitchen treads a thin line between overconceived and just plain ordinary. Many of the principal ingredients in these dishes could use more flavor. A few of them that are full-flavored are masked by a surfeit of sauces and side dishes.

Take the eponymous grilled Hawaiian opah. This is a big hunk of fish, but it doesn’t have any real taste beyond its sesame ginger glaze. Then there is smoked applejack brandy barbecued ribs, perfectly tender pork obscured by a thick, overbearingly sweet barbecue sauce.

A 12-ounce dry aged Angus filet with mustard and rosemary should have been just fine, but mine was overcooked. Farm-raised Atlantic salmon is marinated in citrus juice and rubbed with molasses, which adds gratuitously to the fish’s natural sweetness. Hazelnut crusted halibut is flaky and finely textured, but the flesh has a rather neutral flavor.

And I wasn’t overly taken with the desserts, although they all look good in print. The old-fashioned root beer float with a gingersnap is the best of the bunch, especially if you are into nostalgia. A grainy lemon sorbet served in a pastry cup is improved by a nice raspberry sauce. Chocolate bread pudding with bourbon vanilla sauce is mushy.

But since Day One, Opah has been a runaway success, and it doesn’t seem to be letting up one bit. Oh, by the way, if you came for Greek food by mistake, Daphne’s Greek Cafe, which serves traditional Greek dishes, is directly across the pedestrian walkway.

Opah is moderate to expensive. Small plates are $5 to $9. Land and Sea dishes are $13 to $23. Desserts are $5.

BE THERE

Opah, 26851 Aliso Creek Road, Suite C, Aliso Viejo. (949) 360-8822. Hours: 11:30 a.m.-10 p.m. Sunday-Thursday; 11:30 a.m.-11 p.m. Friday-Saturday. All major cards.