Who is this cheery man in a green sweater following the minstrel's every step through Las Cazuelas? Vincente Castaneda, the mustachioed guitarist, doesn't seem to mind. Every verse of the Mexican love ballad he croons is followed by an enthusiastic chorus from the man in the green sweater. "Oh, that's my father," our waitress, Teresa, tells us. "Give him a tequila and he'll sing all night." He'll have to bring his own bottle, of course, since this restaurant has no liquor license. But since Armando Aguilar's son Alfredo owns this charming little eatery, he has plenty to sing about, even without the extra spirits. Here on the northern frontier of Northern Liberties, in the brightly painted, tile-floored confines of this affable corner restaurant, which sits fringed by banners in the shadow of the St. John Neumann shrine, the Aguilars are serving rustic Mexican cooking with a sincerity that is hard to find. You won't find those tired Tex-Mex cliches here, the gloppy beans and cheese-gooed nachos. Neither will you find a Frenchified pastiche of upscaled Latino flavors that is working its way into the mainstream of fine dining. This is pure home fare, from a family repertoire with roots in the Azteca cooking of Puebla, south of Mexico City. There are refried beans, but they are fresh, beguilingly light in a pinkish mist of mashed bean gravy. There is Mexican rice, infused with chicken broth and studded with little dice of fresh-cut veggies. There are soft corn tortilla tacos, topped with soft sweet slivers of beef tongue, onion and cilantro. And there is the intriguingly dark mole poblano sauce, rich with an edge of chocolate, cinnamon and almonds, that tingles with spice and just a fruity hint of banana. It shadows tender chicken two ways, a solo breast (slightly overcooked but still tasty), or wrapped inside soft enchilada tubes of corn tortilla. Alfredo's mother, Teresa, keeps a close watch over her son as the mole pot simmers, making sure that both the sauce and his temper don't boil. "When you're in a bad mood she won't let you cook; she says it affects the food." With precious few exceptions (the sour glass of gazpacholike tomato juice that doubled as "shrimp cocktail" being one), it was obvious that good humor rules Las Cazuelas' kitchen. With modest ingredients used to best advantage for dishes that are both skillfuly crafted and affordable — entrees top out at $13.95 — it would be hard to leave here grumpy, or hungry. A surprisingly diverse range of chiles are used with authority, tuned to different shades of heat that highlight various dishes without rising above a controlled burn. Deep red guajillos add their sweet spark to the earthy broth of mole de olla beef stew, or play off the musky marinade of the achiote and orange juice that gives the tender pork chop its tang. Smoky chipotles lend their woody fire to grilled shrimp, then elevate a modest cut of beef medallions into something special, gutsy and addictive. A large poblano chile stuffed with cheese almost had the mildness of a roasted sweet pepper — quite a contrast to the tuna-stuffed jalapenos, the only dish that lost its handle on the burn-o-meter. I nearly passed out from their capsicum voltage, which tugged at my ears like invisible sweaty fingers, pulling from behind. Even Alfredo, I later learned, says he doesn't eat this dish. It is always a bonus, amidst such robust cooking, to find softer-flavored dishes to buffer the meal. I particularly loved the tacos dorados, tightly rolled tubes of tortilla-wrapped chicken breast, crisply fried then streaked with a saucy Mexican flag of green, red and white. A chicken breast stuffed with cheese highlighted the bright tanginess of its mild green tomatillo salsa. The thin strip of broiled beef flank — tender and not overcooked as thin cuts often are — sprang with the coriander vibrance of its herby chimichurri marinade. The puffy tortillas called sopes were also ideal for tamer flavors, a comforting little hotcake topped with refried beans, mildly spiced tomatoes, and onion. My complete respite from peppers, though, was gratefully only brief. A wonderful soup special, filled with pureed fresh corn and crushed epazote weed, shimmered with a measured pique of jalapeno. Even the big, refreshing salad came with a splash of heat, brushing a demure cilantro dressing with a little cha-cha-cha. A bowl of melted Oaxaca cheese was swimming in the orange oil of crumbled chorizo, but the combination of resilient salty cheese and spicy sausage made it impossible for us to stop eating. You will find nothing but sweetness when it comes to dessert, but this limited selection was more ordinary — and less consistent — than the savory menu. Sometimes the rice pudding was sticky and undersweetened; at other times it was creamy and bursting with plump raisins. Sometimes the flan was firm and rubbery; other times it was soft and rich. Even the classic dairy-soaked cake called tres leches had some drier nights than others. But I prefer to dwell on its finer moment, when a cream-heavy morsel of sponge cake disappeared from my fork like a cool liquid cloud. I looked up from the plate just in time to bid farewell to Vincente and Armando. "Gracias!" I call out as their act meanders into the next room. Vincente stops at the doorway with a dramatic sweep of the hand, as if to say this food was more than worth the tune: "Buen provecho."

Craig LaBan's e-mail address is claban@phillynews.com.