WHEN IT COMES TO DINING in Portland, most restaurants do the funky, the hip, the casual and even the gritty quite well. We Portlanders feel comfortable in these elements. But the truth is, when it comes to “fine dining” at a mature and polished restaurant, we’re often not so accommodating.

Of course, it may well be that we’re jaded, having watched several Portland restaurateurs attempt such refinement but fail quite miserably at it. But Kevin Gibson and Monique Siu have succeeded—and since opening their elegant restaurant Castagna in 1999, with Gibson heading up the kitchen and Siu overseeing the dining room, they’ve become two of the most respected restaurateurs in town. While its debut was met with citywide acclaim, the sleek, minimalist dining room has been somewhat overshadowed by the more casual (and wildly popular) café the pair opened next door two years later—the kind of place that appeals to the inner fleece-wearer in us all. But with its extremely professional, unobtrusive service (see “Waiter of the Year,” p. 91), a modern atmosphere at once serene and sophisticated, and a refreshingly subtle Italian- and French-inspired menu, Castagna has undeniable staying power.

An elegant black cod is drizzled with sweet cicely cream.

Having cut their teeth at Bruce Carey’s Zefiro—itself a successful fine-dining restaurant here in the 1990s—Siu and Gibson offer fare that will appeal to any diner, but not at the expense of the nuance sought by those with a more discerning palate. Case in point: A simple piece of coho salmon, grilled medium-rare and served with beans, potatoes and aioli. Where other restaurants might settle for garden-variety green beans, Gibson offers long snake beans (also known as Chinese long beans) whose earthy sweetness elevates the salmon’s unique flavors. The potatoes are the Charlotte variety, with a buttery texture that perfectly complements the moist fish and beans. And the pinch of saffron in the aioli makes all the difference in the dish.

Other combinations likewise transcend their singular parts. An elegant plate of sautéed black cod is drizzled with a sweet cicely cream, sprinkled with steamed cockles and topped with julienned cucumbers and zucchini. Corn soup with crawfish and chives, flavored with nothing but salt and pepper, tastes sunny, golden and sweet. And tiny agnolotti filled with mascarpone and mashed shell beans melt into heavenly, savory air upon hitting the tongue.

Each dish is prepared quietly and humbly, yet their flavors are transformative—culinary riffs akin to the strains of John Coltrane and Billie Holiday that often twinkle through the decidedly refined candlelit room. 1752 SE Hawthorne Blvd, 503-231-7373