Have our little BYOBs grown up?

Intriguing new ones, to be sure, are still trickling in. But the phenomenon that in many ways defined the Philadelphia restaurant boom for the last decade - and a story line of small, chef-driven dining rooms - has matured to the point where some of our best are growing beyond the start-up ambitions of their initial bare-bones boxes.

Just last week, in fact, Marcie Turney and Valerie Safran announced that their first hit, Lolita, would become the latest to go down, swapping its virgin Margarita-mix innocence for a liquor license. Others have added side markets (Pumpkin) or sibling restaurants with liquor licenses (Blackfish begat Mica and Ela).

An all-out move was the recent answer for Fond - albeit to just around the corner - the bistro whose crispy pork belly helped East Passyunk Avenue keep its culinary ambitions high as it morphed into the city's hottest dining strip.

It was the prototypical Philly BYO: a talented cooking couple, Lee Styer and Jessie Prawlucki, winning loyal fans with French-inspired modern cooking and handcrafted desserts, and a front-house charmer, partner Tory Keomanivong, delivering sophisticated service to its jam-packed and noisy 34 seats.

One couldn't blame this trio for wanting to step up to a bigger dining room with . . . 48 seats?

The gains may be modest in pure numbers. But aside from the revenue boost from a liquor license, the small increase is deceptively huge. It will allow a promising restaurant that had maxed out on space and income to continue to mature as a complete experience.

The corner room is still plenty intimate, but brighter and airier, with cafe windows that will open onto 11th Street in warmer weather, more breathing room between tables, and taller ceilings (and acoustical tiles) to dampen noise that was nearly deafening in the previous storefront. A chef's table hewed from a trunk of silver oak in a room off the kitchen offers possibilities for multicourse tastings and semiprivate gatherings.

In that kitchen, however, the little space gains have been enormous. The virtue of a walk-in refrigerator means Styer can now order ingredients by the case instead of by the bunch, allowing for better economy, greater flexibility for walk-in guests, and more creativity with new dishes. Some of which debut at the bar, like the grilled duck hearts with tahini yogurt and fennel, or a warm terrine of scallop mousse, almost creamy beneath its deep brown sear over a puddle of rich red-wine "beurre rouge."

Though the occasional daring cut may make a cameo, Styer's cooking is built more on good ingredients in smart combinations with a spot-on French approach, rather than on avant-garde techniques.

The food is familiar, but not boring, and the sense of hospitality begins the moment you sit down, a basket of Prawlucki's fresh olive and sourdough breads is delivered, and diners are given a warm shot glass of frothy soup. Ours held a creamy tan brew that was the distilled essence of mushroom, an umami shot to wake the taste buds.

What followed were the same well-wrought flavors that helped Lee, a vet of Lacroix at the Rittenhouse, rise a year ago to three bells in his BYO. Toothy risotto is lavished with a truffled mascarpone lobster froth studded with morsels of tender crustacean and the snap of toasted hazelnuts. Gingery butternut squash soup is poured onto a crab salad whose sweet lumps are ribboned with toasted coconut shavings and the bright exotic spice of green curry vinaigrette.

Tender snails, glazed in fish fumet thickened with hazelnut butter and the delicate crunch of garlicky bread crumbs, pays homage to Lee's stint at Le Bec. And that pork belly, the skin crisped to a cracker over tender layers of juicy meat alongside purple Okinawan sweet potatoes, retains its title as the city's belly champ.

What's most different, of course - and also most fraught with problems - is the liquor license. Hell hath no fury like a BYO groupie scorned.

Fond has nipped some bottle-toter blowback in the bud by continuing to allow free BYO Tuesday through Thursday, with a reasonable $10 corkage per bottle on weekend nights. And nearly three-quarters of the guests still oblige, says Keomanivong.

Making the most compelling use of its small bar, though, is where this bistro has the greatest potential to grow. A few months in, the affordable wine list already has a dozen quality choices by the glass, including some lesser-known varieties (passerina, dry Moscato, monastrell) and familiar grapes from value-rich locations (Pays d'Oc pinot from Domaine Brunet; chardonnay from De Mayo in California's Livermore Valley). The recently added reserve list offers a few worthy high-end options, but they'd be more intriguing if they weren't all available retail (and thus BYO) for a fraction of the price. Fond should also ramp up its small craft beer selection, considering East Passyunk's brew-centric crowd. And though I like the idea of classic cocktails for this list, ours lacked finesse - the weakest part of otherwise lovely meals.

Not that Styer is perfect yet, either. I wish some of his sauces were a notch thicker. His use of nuts can feel redundant. And though he did a fine job of improvising a veggie meal for one of my guests, a composed entrée would been more impressive than a smorgasbord of sides - though the roast acorn squash and onion spaetzle were flat-out delicious.

We had only one real clunker course: a thin and one-dimensional foie gras soup. The special just lacked spark - especially beside his stunning appetizer of crisply seared foie, warm and creamy over cool carrots in gingery caramel with cardamom-spiced cream cheese sauce.

That indulgence was in perfect contrast to the elegance of tuna crudo tiled over piquillo peppers with a white miso aioli, or the beautifully browned swordfish over ivory vichyssoise sauce with tart bursts of grapefruit, bitter watercress, and the salty pop of paddlefish roe. Big, gorgeous sea scallops channeled a Spanish mood over saffron paella rice with smoky chorizo. And the chicken, roasted on the carcass before being deboned and finished with duck-fat-braised Savoy cabbage, was excellent.

That's a good adjective to describe the desserts from Prawlucki, who, now from her Belle Cakery atelier just up Passyunk Avenue, creates sweets that are both elegant and accessible, from her classic malt-chocolate ice cream with delicate peanut brittle to a fluted pastry cup brimming with saffron-poached apple balls that look like golden marbles.

It also happens that this is when Fond's fledgling wine list shines best, with a half-dozen exceptional pours - Tokaji, sauternes, Rare Wine Co.'s Savannah Verdelho - that can be the ultimate by-the-glass icing to that special bottle you may have brought for the rest of the meal. Call it BYO-plus. And maybe the best of both worlds.