“Ask not what your country can do for you,” Orson Welles once said. “Ask what’s for lunch.” It’s fair to assume that when the big man posed that question, “foie bonbons” was rarely the reply. Times have changed, however, and the sweet-and-savory snacks are now read­ily available—albeit for dinner—at Elizabeth Falkner’s Orson, a culinary laboratory south of Market Street.

“People either love or hate them,” our waiter told us as he served the palate-teasers, bite-size spheres of foie-gras mousse enveloped in a hardened chocolate shell. He might have said the same about the restaurant.

Like its convention-shaking namesake, Orson isn’t after your neutrality. In the months before it opened, the restaurant received the kind of media buildup normally reserved for summer blockbuster movies. Some of the buzz revolved around Falkner, the big-name chef behind Citizen Cake. But a good deal of the hoopla had to do with the concept, which promised to play wildly with diners’ expectations by casting ingredients in unlikely roles: chocolate on pizza, bacon in dessert. Falkner knew the rules but chose to break them, departing the world of Alice Waters to join Alice in Waterland.

In San Francisco, where straightforward farm-stand cooking holds strong sway, it doesn’t take outlandish stunts to qualify as nonconformist. It does takes courage, though, and Orson is anything but shy.

The restaurant’s website boasts of “edgy” California cuisine, an unfortunate adjective that makes anyone who uses it seem instantly less so. More accurately, a meal at Orson is a little odd, replete with offbeat pairings and postmodern flourishes that sometimes tantalize you with intriguing flavors, but just as often simply leave you scratching your head.

Falkner and her chef de cuisine, Ryan Farr, ornament their menu with molecular maneuvers, frothing butter onto carrot dumplings and bathing house-smoked trout in sweet-corn foam. Parmigiano pudding embodies the aesthetic: The soft, flanlike dish comes with piquant pepper jam and is sprinkled with what’s described as a “cocoa nib explosion.” The nibs are, in fact, cocoa-dusted Pop Rocks that provide a mini-burst with every forkful. The tongue-in-cheek nostalgia they engender adds to the pleasure the dish imparts.

Orson’s kitchen is capable of razor-sharp technique, and when that technique combines with

inspired invention, dinner brings original rewards. A salty tongue croquette with tarragon and sea beans finds the perfect tarty partner in roasted cherries. A tempura-battered egg, its surface spiked and crunchy and its yellow innards runny, splash-lands like a welcome spacepod in a bowl of scallion bouillon. The contrasting tastes and textures, as the rich yolk spills from its crisp coating into a bright, seaweed-seasoned broth, are both unusual and delightful. It’s a foreign dish that feels right at home.

Yet, as many experimental ventures do, Orson often spirals out of control. Chocolate-and-espelette pizza drizzled with olive oil and sea salt sounds plausible enough, holding out the promise of heat balanced by sweetness—but its doughy crust is slathered in so much gooey chocolate that the dish becomes cloying, a Starbucks pastry passed off as a main course.

Sometimes Orson’s problem is muddied execution. At other times, it’s a flawed idea. A pillowy pork bun with chilies, cilantro, and maple syrup has such a stingy filling that all you taste is its pasty outside. As for the foie bonbon, its buttery mousse contains only trace elements of fatty liver, just enough to spoil its chocolate shell. It’s not the War of the Worlds, but it is a dish at war with itself.

Like a zany installation at a modern-art museum, Orson’s avant-gardism provides vulnerability and a shield at once. Detractors will be quick to brand it as pretentious, while critics may pull punches for fear of seeming like they just don’t understand.

Count me, then, among the mystified. My problem with Orson isn’t its approach. Other Bay Area restaurants (Coi, Ubuntu, and Rubicon, for example) have dared to be different—but few have managed to feel so contrived.

Orson’s sense of willful hipness—its self-proclaimed edge—carries through to its decor. The restaurant occupies a onetime steel foundry, with its ceilings blown out to reveal its warehouse origins, and a newly constructed catwalk running amid the rafters. A bookshelf, stocked with staged-looking design texts, separates the front room from a U-shaped marble bar, which makes a decent spot for one of many well-mixed cocktails. On the upside, there’s a lush celery gimlet. On the downside, a montage of art images runs silently and cease­lessly on the rear wall, an overeager stab at chic that might have seemed

groundbreaking 20 years ago.

In this mannered setting, the waitstaff work with ease and expertise, fielding far-flung questions about the quirky menu. A Norcal, they’ll inform you, is creamy chèvre rice pudding with dates, olives, kumquats, and flaky walnut “paper.” A pigwich, for its part, is a crisp pizzelle with maple-bacon ice cream. It tastes, not surprisingly, like chilled pork fat.

Orson Welles no longer dines among us. But you can almost hear the great director saying, “No, seriously. What’s for dessert?”

508 4th St. (at Bryant St.), S.F., 415-777-1508 $$$ 1½ stars