The bentwood chairs at Mr. Martino's wobble and creak with various degrees of age and comfort. And though the staff is graciously patient with those who fuss and switch until they find the perfect seat, don't expect a decor makeover anytime soon at this South Philly classic.

"We couldn't bring ourselves to buy new chairs," owner Marc Farnese said as he swapped out my chair for one that still had a back. "It just wouldn't feel right."

After 18-plus years inside this dimly lit haven of homey Italian cooking, a former 19th-century hardware store whose chestnut-paneled room is hung with antique paintings, lacy curtains, and old family photos, a few quirks are to be expected.

But few Philadelphia restaurants revel in the reclusive embrace of their eccentricities quite like Mr. Martino's, the cash-only, weekend-only trattoria that's so low-key, its owners would rather be overlooked altogether.

"I don't think this is going to work out," cook and co-owner Maria Farnese wrote me in an e-mail after learning of a planned review. "I don't want to waste your time."

After a pair of meals built on polenta and sausages, simple but satisfying soups, and one of the city's most distinctively moody rooms, there wasn't much chance of that.

The restaurant itself could easily be missed entirely amid the bustle that now energizes trendy East Passyunk Avenue. While Cantina Los Caballitos explodes across the street with margarita-fueled hipster throngs - the windows swung wide open and every inch of sidewalk planted with a table - there's little more than a quiet storefront and a dangling hand-painted sign of a four-legged table marking Mr. Martino's turf.

The Farneses, who've been here long enough to remember when kids played halfball in the now-jammed parking lot beside their building, like it that way. Pull the brass-handled door and step into the oddly angled room, where classic jazz floats through the air and Marc is posed behind the bar refashioned from the hardware store's antique nail bin. The modern pace of South Philly fades like a memory.

"We've only got 50 seats and a six-burner stove with Maria alone in the kitchen," says Marc. "A lot of people have missed their movies coming to Mr. Martino's."

Maria's reluctance to be held up to "foodie" scrutiny, though, speaks volumes to the essence - and limitations - of this BYO, one of the last vestiges of the homespun spirit of our first Restaurant Renaissance. Inspired by their frequent visits to Italy and launched as a career-changer (Marc sold antiques; she commuted to New York as a fabric designer), Maria's menu has grown ever so slowly as she taught herself to cook through books and the solitude of her kitchen routines.

"I'm a cook, not a chef," she says straight out. "And I cook like a housewife. I cook everything during the day, then reheat it for service."

No doubt, the home-style cookery from this kitchen is so simplistic, it's not for everyone - especially those steeped in the sophistication of today's scene. Even a decade ago, during my first Martino's visit, I recall thinking that this food was a bit too plain.

But recently, once seated on a stable chair beneath an antique lamp of a boy blowing a lightbulb for a bubble, something clicked.

The simple clarity of Maria's best dishes rang like a soulful ping on my taste buds. The pasta and bean soup was an ode to pure peasant textures, the soft white beans against the chew of pasta rings, and a bean broth lit with the piney herbaceousness of panfried rosemary.

House-baked wedges of ricotta cheese are one of the standby starters, a cold appetizer that disappears no matter which garnish comes on top - string beans and juicy grape tomatoes tossed in herby vinaigrette, or chewy rounds of Claudio's soppressatta and oil-cured olives.

Without much flourish to her compositions, Maria is quick to tout the pedigree of her local purveyors, with fresh stuffed pastas from Nino's and Talluto's, great Italian sausage from Fiorella's and Cannuli's (on Ritner), Michael Anastasio produce, and chuck from Harry Ochs that simmers into the tomato gravy. That meat-infused ragu (the beef is removed for a special with kidney beans) is key to my favorite dish, smothering the wedges of polenta and roasted sausage with slow-cooked richness.

But those building blocks make their case in more austere dishes, too, like the cheese ravioli from Nino's that get shined with a gloss of nutmeg-speckled butter beneath slivered asparagus. Even the bread served with sun-dried tomato oil is a matter of considerable discussion, with Mr. Martino's faithful divided between those who visit for crusty Faragalli's nights (Friday and Saturday) or puffier Varallo's (Sunday).

Maria's precooking method works well enough for most of the menu, especially indestructibles like the balsamic-roasted chicken, or the "pasta fagiole" entree of rigatoni and hearty white beans with spicy broccoli rabe.

Grandmotherly desserts like the deliberately undersweetened tiramisu (with homemade ladyfingers), or the tart lemon curd pastry, or the spongy genoise with strawberries and creme anglaise, or the decadently retro chocolate pudding, survived and satisfied without a hitch.

In dishes that require a little to-order finesse, however, Mr. Martino's can use work. Entrees with reheated boneless chicken breast were dry. Penne with fried zucchini was filled with spears of limp squash. The broccoli rabe - so effective as a bitter counterpoint to the pasta - was, on its own, a bowl of bitter, stringy, off-green mush.

Most problematic, though, was a risotto special that was flavorful but full of rubbery bay scallop nubs. There's an easy way, of course, to extract the mollusks' full flavor for the rice without overcooking the final dish (a simple stock - with fresh scallops added at the last minute - would do). But that might require a change in the routine.

"We're just a crazy little restaurant and we can't change. This is who we are," Marc said without a hint of defensiveness, amazingly, after I'd sent my dish back. "Can I get you something else?"

You bet - another plate of sausage and polenta, please. Once you get to know (and embrace) Mr. Martino's many quirks, it's easy to see why it really doesn't need to change.