One minute they're adding an Asian lacquer to their duck confit with a salsa verde flourish (a perfectly fine idea). Next thing you know, they're crumbling fried pork-skin crispies atop the chocolate gelato - an Iron Chef-like fantasy, no doubt, but one that in reality tastes as awful as it sounds.

So it's no wonder the fusion trend, after a couple of decades in fierce flower, has been evolving to a more sensible ebb. The focus has shifted to updating authentic dishes with good ingredients and contemporary techniques, rather than simply grabbing a jumble of flavors out of context and reassembling them just because you can.

It seems that Ben Byruch, though, has other ideas.

"I basically like to have no boundaries," says Byruch, 25, whose "global dim sum" small plates at Sonam on South Street would make a cartographer's head spin.

You can go from Asia to New Orleans to Africa in a few creative bites in this sleek subterranean BYOB, just a few steps down from the South Street sidewalk. And the best of his dishes speak well of Byruch's precocious talent and wit. A number of other less successful efforts, though, reveal a young cook whose technique hasn't quite caught up to the racing mind, for whom a few more boundaries might actually be beneficial.

Among the most memorable were the "hamachi nachos," tortilla chips topped with yellowtail sushi and a spicy streak of oil infused with the essence of pico de gallo. There is also a memorable savory trompe l'oeil twist on S'Mores, in which broiled goat-cheese "marshmallows" sit atop the chocolate lookalike of reduced figs and whole meal crackers for a clever campfire twist on the cheese course.

The Asian chicken sliders - three brioche-bun minis topped with a ponzu mayonnaise - are among the best poultry burgers I've ever had. Granted, that's not a high bar, but I've actually come to crave these moist and gingery little patties.

I also might have loved Byruch's take on andouille and crawfish gumbo, which came wrapped inside a spring roll with a sweet duck-sauce dip blackened by Cajun spice. But the ricey gumbo filling had the unpleasant texture of mush.

With small plates, every detail counts. Every texture, every flavor. And while the challenge of pulling off a menu of nearly 20 wide-ranging dishes is high, too many of Sonam's offerings seemed to be missing a final touch.

The South Philly Negamaki was a neat idea, with long hots, broccoli rabe and provolone rolled into a tube of Italian roast pork. But by the time the preciously stacked pork-roll plugs hit the table glazed in sweet soy, the meat was dry as leather. I loved the smell of the macaroni and cheese laced with queso blanco and pico de gallo, but the crumbled tortilla crust was chewy, and stuck in my teeth like toffee.

The cold soup duo served in edible cucumber and Asian pear cups was clever, but the soups themselves were wildly overseasoned with ginger and chile spice. The big tortoloni tossed with mint pesto and filled with Moroccan-spiced lamb, meanwhile, was noticeably undersalted.

Melting mozzarella atop nuggets of chicken tikka masala cradled in wonton crisps was a nice Indian wink to chicken parmesan, but the chicken bits were rubbery - and, at $9 for three, seemed expensive.

Another disappointment were the $14 "lobster rolls," lobster meat and mangos wrapped in a phyllo tube that was so overwhelmed by the aroma of vanilla, it was like eating a fishy pastry. The tiny minced bits of claw meat hardly merited the price.

The vanilla-lobster pairing is a dicey one I've rarely enjoyed, but I can't blame Byruch for trying. He's got an adventurous spirit and ambition, stoked early by a childhood tagging along with his father, who was a meat distributor to local restaurants. He honed his skills at culinary school, worked for chefs including Michael Schulson at Pod and Guillermo Pernot at Trust, did banquet time at the Desmond Hotel in Malvern, then the Brickside Grille in Exton.

After a subsequent two-year stint out of restaurants (doing food sales), he leaped back into cooking when the former Next BYOB space came open on South Street, offering the chance for his own place. It's always been an odd, somewhat claustrophobic underground room, but Byruch has done a nice job of warming it with earth tones, pale wood floors, and cushy banquettes with dangling rice paper screen to divide the seats.

He's also taken the accoutrements of drinking as seriously as any BYOB, with specific glassware for everything from sake to martinis, and house-made mixers (pomegranate margarita) ready for your booze.

The servers are also well versed on the menu's intricacies, though their attitudes - downright perturbed and curt one night, warm and helpful the next - were as inconsistent as Byruch's cooking.

Will you get a winner like those deep-fried cubes of gruyere cheese over tomato soup? Or an overthought dud like the deconstructed paella, a squishy coaster of saffron rice topped with chorizo oil and lightly torched raw sea bass cut so thick it was difficult to chew?

Byruch, I have true confidence, is talented enough to settle down, mature and focus. But the roller-coaster plates wouldn't stop before dessert. Pressing brioche bread pudding into a waffle-ironed crisp was a brilliant idea, my new favorite pedestal for a la mode. But he couldn't resist joining the long list of chefs who have done naughty things to creme brulee, this time adding so much lemongrass it was like spooning through soap pudding.

Our journey really fell off that narrow path into the wilderness of bad fusion flavors, though, when I took a bite of the chocolate gelato. What was that salty, piggy chicharrone crunch?

The flavor of a young chef with promise still finding his way.