First came the toro, or fatty tuna belly, as marbled as the Taj Mahal. It was cut into slabs and stacked on shiso leaves with a crown of shaved daikon, a regal dish awaiting a soy and mustard bath. The seviche showed up next. Sweet slivers of fluke had been quickly dipped, not soaked, in citrus, so the acid trip they took you on was brief and bright. The fish itself came wrapped in watermelon radish, sliced thin to resemble pink rose petals. The radish offered texture. Red bird’s eye chilies finished off the flavors with a fiery kick.

In the partly open kitchen, chef Hiro Sone was busy wrapping poke—his sesame-scented medley of striped bass, fluke, and grouper—in fragile strips of seaweed and quickly frying it in a light tempura coat. At the sashimi bar, meanwhile, diners clicked their chopsticks over sea bream, which came layered over disks of monkfish liver, as smooth and sweet as fine foie gras.

Since 1989, Sone and his wife, Lissa Doumani, have run Terra in St. Helena, a restaurant that speaks to the cross-cultural heritage of the couple in charge. In the quaint surrounds of wine country, Sone’s Japanese accents come through in hints and whispers. But here at Ame, the couple’s new restaurant in San Francisco, they ring loud and clear.

Ame (which means rain in Japanese) sits on the ground floor of the St. Regis Hotel, a sleek tower that overlooks the South of Market district like a fashion model sizing up a cocktail crowd. Silver and gold curtains shroud the windows of the restaurant, providing passersby with just a shadow-puppet glimpse of what’s going on inside. The dining room itself is cool but not self-conscious, fancy but not fussy, a space that smartly takes its cues from the nearby Museum of Modern Art. Mesquite floors and travertine walls make a graceful first impression. Bowed beams of sculpted wood frame the entrance like parentheses.

Some hotel restaurants suffer from corporate seriousness. Ame acts adult without losing touch with its inner child. Large silk lanterns float above the room like psychedelic sea creatures. The place feels trendy without trying too hard.

Sone and Doumani describe their menu as New American cuisine, a gentler way of calling it a melting pot. As at Terra, the flavors of France and Italy turn up on the menu, tempered by modern touches. Rich duck ravioli arrive with a scattering of giblet confit. Spaghetti “crabonara,” a less weighty version of the classic, is sweetened with chunks of Dungeness crab.

Although the fusion in each dish is exceptionally fluid, the overall progression of a meal can be jarring. Opening an evening with “Lissa’s staff meal” of cuttlefish noodles—the cuttlefish stripped into ribbons and tossed with quail egg, sea urchin, daikon, and soy sauce—then moving onto burrata (mozzarella’s creamier cousin) with braised artichokes is like going to bed in Tokyo and waking up just north of Tuscany when, really, you had no reason to leave. The cuisine of Western Europe is all well and good, especially when it gives rise to a simple radicchio salad, in a dressing justly governed by parmesan and lemon. Or a grilled pork chop in a Dijon-wine reduction that’s twice as thick as the average chop but twice as tender, too. Still, the stars of Ame’s constellation of dishes are those visible from the Pacific Rim. They include an upscale rendition of chawan mushi, a homey egg custard that is often served to babies in Japan. Sone’s adaptation—with lobster meat and sea urchin in suspended animation in the silken custard—is only for children who have been very good.

At Terra, Sone created what has come to be considered his signature dish: grilled sake-marinated Alaskan cod with shrimp dumplings in shiso broth. To taste this entrée is to understand why Sone brought it with him to the city. The cod has a sweet, almost candylike coat to brace against the gentle bite of shiso, and it flakes apart at the faintest prodding with a fork. It’s the kind of dish that makes you pause with pleasure at first spoonful, the hand holding your silverware frozen in midair.

Ame seems poised to take its place among the city’s small rotation of destination restaurants. It has service to match the easy elegance of the ambience, an eclectic wine list, and an equally creative collection of filtered and unfiltered sake. If desserts are lacking, it’s not for quality but congruity. More sweet than subtle—like dense hot chocolate with churros and key lime pie that comes up all crust and meringue—they feel faintly out of place.

The same cannot be said of Sone and Doumani. Their superbly executed, unconventional restaurant is proof that things can work the other way around: a wine country success can make the city its second hom.

Ame, 689 Mission St. (at Third St.), S.F., 415-284-4040, $$$. Reservations Recommended. Valet Parking. Wheelchair Accessible. ***1/2