Few diners - and for that matter, few critics - really know what goes on in the kitchen. And whether it's fair or not, both the glory and blame for dinner ultimately go to the chef. Fine dining is a performance business where the cooks must bring it every night with pans a-blazin' - not a side of excuses. And the reviews will fall where they may, inevitably coloring our impressions of the talents behind the stoves.

As I wound through my disappointing review meals earlier this year at the old Le Bec Fin, however, the picture taking shape of chef Nicholas Elmi was perplexing. Persistent flashes of modern brilliance were interspersed with loveless and flawed renditions of classics, eroded even further by comically bad service: The talent was obvious, but it was not in a good place.

I didn't know Le Bec was actually then in its final days. Owner Georges Perrier, after all, had cried "loup!" for years. But things had crumbled behind the curtain so completely, Elmi recently told me, that he often didn't even have enough plates - and had to wait for early diners to finish eating so dishes could be quickly washed and then sent out to the hungry in waiting.

There are plenty of dishes and support staff at the new Rittenhouse Tavern, and maybe now a chance at redemption, too. It's true for Elmi, 31, who, now more relaxed to cook the food he loves, is creating artful contemporary plates that are recasting him as one of the city's top young chefs. But it's also true for the Philadelphia Art Alliance's restaurant itself, a uniquely elegant dining space that has gone underused for years.

Few restaurant spaces evoke the feeling of classic Philly grandeur quite like this 1906 Italianate palazzo, from the hideaway back bar to the sunny mansion dining room with French doors ringed by the vintage mural of a misty bronze Asian summer, to the walled back garden where diners nibble crudo and tempura-crisped soft-shells in rare urban quietude just a few steps from Rittenhouse Square.

Not since the days of Opus 251 a decade ago, however, has a kitchen here been turning out such vibrant cuisine. That crudo of local fluke, cured in kombu before being layered with sheer radish chips and silky dabs of lemon puree, was one of the best bites of raw fish I've had in months. Sweet summer corn, steeped into intensely flavored cool milk, is poured tableside into a bowl, sending an aromatic bloom of brown-butter foam rising toward a wafer-thin prosciutto blade that spans the rim. That ham cracker was topped with lightly smoked blueberries, elderflower puree, and freeze-dried corn. Crumbled into the soup, it created an intricate but vivid mouthful of earthy savor, sweet, cool, and crunchy.

The Tavern, with its side bar and bare dark-wood tables, makes an attempt to retain a hint of casual spirit, with some fresh takes on familiar American flavors. The house burger, made with good LaFrieda meat, provolone, and a whole wheat bun fermented with Yards E.S.A., is instantly one of the neighborhood's best. A spicy egg-yolk mousse piped atop crispy cubes of pig trotters fried in an oatmeal-corn crust captured the deviled-egg and scrapple trends in a single bite.

There are crisply fried portobello "fries" with ponzu dip, and addictive little bowls of house-pickled veggies - thumbelina carrots and watermelon rinds! - with cool herbed yogurt. Only the Sunday fried chicken dinner, bland and boring, was a down-home disappointment.

It's clear from much of the menu, though, that Elmi's French influence is still a strength, no doubt the inspiration for those adorable frog poppers - lollipops of crispy frog legs collared with a hot-pepper ring and stuffed with cheesy mousse. Elmi's numerous terrines showed a craftsmanship that was superior to what I found at Le Bec, especially obvious on the gorgeous sampler board laden with rabbit rillettes, brandied country pate, and an exquisitely layered parfait of rare quail breast, quail rillettes, and creamy foie gras.

It is Elmi's artful yet sensible mastery of contemporary techniques here, though, that may surprise some.

Most stunning was the "shrimp pavé," a tender pink brick of Moroccan-spiced crustaceans bound with Activa "meat glue" into a geometrically perfect Franken-shrimp. Slow-cooked sous-vide, its delicate snap and faint exotic spice was ideal against the sweet juicy bursts of multicolored melon and crackly curls of pork rinds. Sous-vide vacuum cooking is the key to Elmi's vegetarian entree, too, tenderizing a thick heart-slice of cauliflower "steak" before it's butter-roasted over silky cauliflower-almond oil puree.

Dehydrated black and green olives add a pop of piquance to sweet peaches and earthy sunchoke sauce that frames beautifully seared turbot. Fried farro grains bring texture to the succulent scallops and truffle-buttered Hakurei turnips. Black quinoa grains and brioche crumbs add a toasty edge to the superbly juicy pork chop, which came with melty pork-belly croutons and purple mustard.

By contrast, the crab-cake balls over mustard sauce (an obligatory dish for locals, judging from Elmi's sigh) were pure meat, but somewhat dull. One of the more interesting ideas, a Burgundy sauce rendered tangy and deep purple with hibiscus flowers, was lost on an overcooked piece of bass - one of the Tavern's few technical miscues.

The service staff is young, but outgoing and prepared. They did a good job with wine suggestions from a relatively small list for food of this caliber (especially with reds), but one that offers some appealing choices at reasonable prices. I wish my Paloma Fizz cocktail had both more finesse and a little more oomph to make the most of a cheffy house mixer like keffir lime soda. But there are several craft beers (Twin Lakes, Goose Island), and some fine Scotch ("Peat Monster," Highland Park) to compensate.

The Rittenhouse Tavern finishes strong with some memorable desserts. A wonderful ode to summer cherries is a lightly set pâté of crimson fruit over a graham crust topped with slivered golden cherries and pistachio ice cream. A brown butter cake with fennel jam and sour cream sorbet hit another level when the waiter doused the cake tableside with a drizzle of sweetened fennel juice. The usually savory and faintly bitter anise took on a sweet golden luster as a dessert.

Likewise, a talented young chef has dusted off the debris of recent history, and is heading toward a golden future once again.