In November, Jane G's fancy fusion dumplings looked deader than disco. Who could have guessed that, by the New Year, this kitchen would be revived and breathing Sichuan fire?

At my first meal, the ornately carved wooden dragons lining its mezzanine banisters had no reason to roar. The sleek, modern dining room - with plush white seating for 125 - was virtually empty.

The reason for the stunning lack of patrons was clear: Jane G's pricey menu was one big, dull, pan-Asian fusion cliché. From the rock shrimp with wasabi aoili to the lobster mashed potatoes, it appeared to have been conceived after a long nap that began in 2003.

That is the year Jane Guo closed Noodle Heaven, her long-running, theater-district Chinese stalwart, and headed for Panda Heaven projects in Pottstown and Reading.

Nearly a decade later, after a nearly $2 million rehab of an old Blockbuster at 20th and Chestnut for her Center City comeback, Guo quickly learned that much had changed for Philly's taste buds. Watered-down fusion food was out. Bold takes on authentic ethnic flavors - with Sichuan bad boy Han Chiang blazing the trail at Han Dynasty - was hitting a "10" on the hot list.

Of course, any restaurant consultant could have looked at Rittenhouse Square's high-toned clientele, long beaten into takeout submission by a roster of bland American-Chinese options, and concluded: "These people need a dose of chile oil with spicy kidneys and tripe!"

OK, maybe not. But that's the risk that Guo and her son, general manager Jackson Fu, have ventured upon.

"The original concept was a mistake, frankly," Fu says.

Their bold move has paid off.

Tender pork wontons arrive with a two-toned splash of sweet and spice - a rich Sichuan brown sauce ringed by an aurora of sunfire-orange oil. At my table, chopsticks battled over the "Beef Lovers Quarrel," a chilled mound of thinly sliced beef shin (stewed with five spices), translucent sheets of snappy tendon, and frilly shavings of tripe, tossed in a classic Sichuan marinade. This blend of chile paste and oil lit with roasted red chiles and fagara - the famous peppercorn that distinguishes Sichuan's numbing heat from the one-dimensional spice of other regions - has a prickly heat that contrasted with the meat's cold temperature, heightening the aromatic effect.

There are several fine items that don't demand asbestos palates - the meltingly soft tubes of Asian eggplant glazed in mellow brown garlic sauce, the sesame-tinged brussels sprouts, or the crisply fried Cantonese shrimp drizzled with sweet orange sauce with honeyed walnuts. It's a Noodle Heaven classic.

But the dramatic increase in business (a sevenfold increase, Fu says) is responding to Jane's new Sichuan groove, legit since the New Year's Day debut of chef Yu Cai Xue and his cold-appetizer accomplice, Shao Ying Li. And you'll have to ride the heat scale from 1 to 5 if you want to understand what makes their food such a draw. I'd suggest 3 as a baseline for those who can handle some spice, which is necessary for the spirit of this food.

Nowhere is the magnetic power of that nose-tickling fagara-chile combo more convincing than in Xue's special "Spicy Perfume-Style Fish," a basin-sized bowl in which velvety white pads of flounder bob alongside bullet-shaped red chiles, threadlike clusters of enoki mushrooms, leeks, and vermicelli noodles, in a broth that swirls with cinnamon, clove, cardamom, fennel, and bay. Nudge the spice level up, and it's like giving a twist to the volume dial.

The Han Dynasty comparisons are to be expected, said Fu, who acknowledges Chiang's impact. Jane's polished decor is certainly a plus. But several dishes still lack just a notch of Han's edge. The dan dan noodles, twirled tableside in a glaze of sesame paste and minced pork, have a thinner sauce that leaves less of an imprint. The ma pao tofu is just so-so. Jane G's dumplings are not especially distinguished.

The well-meaning service has improved, but is still ramping up to both understanding the dishes and expertly translating the menu for neophytes. Even so, there are so many distinctive dishes that make Jane G's well worth the adventure. The fish in hot bean paste is one of the best whole-fish dishes in the city, a huge tilapia submerged in tangy brown Sichuan gravy that delivers downy white meat that melts on the tongue.

Xue's tea-smoked duck is also exceptional, the bone-in slices of meat completely infused with layers of flavor from a Shaoxing wine marinade, a dry rub of star anise, clove and jasmine tea, and the sweet smoke of pine wood. Exotic mushroom lovers must also try the unusual agrocybe, the rehydrated stems of imported brown "tea leaf mushrooms" that come stir-fried with green, long, hot peppers.

The crunchy cloud ear mushrooms are also to covet in the stir-fried pork kidneys. But it's the kidneys that are the best surprise, their pinecone-scored curls of meat with the look and texture of tan calamari and a flavor that's distinctive but more accessible than, say, liver.

For those who can do heat, but not exotic meats, Jane G's offers chicken in enough compelling variations that one can still understand what the Sichuan sensation is all about. The kung pao, long abused by take-out phonies, brings cubes of dark meat and roasted peanuts glossed in a spicy-sweet glaze beside dried red chiles. Dry pepper chicken fries those cubes inside an aromatic crust infused with chile oil. "Dry pot" chicken delivers larger chunks unbreaded, simmering in a mini-wok over a bubbling brew illuminated with fagara.

The Singapore mei fun is an excellent rendition of a common dish, the perfumed yellow curry vivid without being greasy, and each ingredient (like those tender shrimp) perfectly cooked. The scallion pancakes are crisp and flaky.

For slightly more adventurous palates, the cumin lamb is a must - less potent than Han's, but still a flavorful mound of tender lamb shreds dredged in earthy cumin and spice. Likewise, the spice-crusted beef "jerky" - flash-fried for texture rather than dehydrated, with a little fat for flavor - is impossible to resist. The shaved cold pork belly starter in sweet garlic soy is, by comparison to the Beef Lover's Quarrel, an easy, familiar comfort.

The same cannot be said for the spicy rabbit with peanuts in chile oil, a cold plate of diced bunny that brings a shard of bone and the full, lip-numbing power of Sichuan spice in every bite. Eating it is an acquired skill of tongue-craft - carefully probing each cube inside your mouth for every shred of flesh and flavor before unceremoniously discarding the remnants onto a plate. It isn't exactly first-date food. But it says a lot about the new Jane G's: surprisingly, uncompromisingly authentic for those who dare. And back in the mix after its false fusion start.

Next Sunday, Craig LaBan reviews Gennaro's Tomato Pie. Contact him at claban@phillynews.com