Meredith Hoffman Porchetta, 110 East Seventh Street.

The supreme realization, or maybe the reductio ad absurdum, of the East Village nano-scale restaurant is the place which serves only one item, and has no room to do anything other than order that one thing. In this regard, I would say that the echt East Village establishment is Porchetta, a shoebox at 110 East Seventh Street, between First and A. It is at least theoretically possible to eat something there other than porchetta – a roast pork sandwich – though it’s hard to see why you would; and you can squeeze onto a stool at the counter, though you’re liable to get trampled by the foot traffic if you do.

What is porchetta that one should make so much of it? Sara Jenkins, the founder, owner and master chef, explains that, in classic form, porchetta is a whole, slow-roasted pig stuffed with herbs and innards, and then encased in its own belly to produce a rich outer layer of crispy fat. Porchetta is street food, and served only in the form of a sandwich consisting of a thick slab of pork and its surrounding fat.

Sara grew up in Rome as well as a little village outside the Tuscan hill town of Cortona. Porchetta is Roman by origin, but in ancient times, as Sara understands it, Cortona fell under the political and culinary influence of the Vatican States. A thick vein of crackling pork thus ran through her childhood. “As soon as we got to the house in Cortona,” she recalled, perched on a restaurant stool during a recent afternoon, “we would run down to the market for a porchetta sandwich.” Many years later, when she was cooking at downtown Italian restaurants like Il Buco, on Bond Street, a friend who worked as a chef in Rome paid a visit and said, “Someone has got to do porchetta.” Sara understood that destiny was speaking. “I decided,” she says, “that it should be me.”

Owing, perhaps, to her Italian background, Sara prefers simple and basic to varied and elaborate. “I’m a big believer in doing one thing and doing it right,” she says. (Her new restaurant, Porsena, at 21-23 East Seventh Street, specializes in pasta.) A one-product-only restaurant was not a problem. Still, she wasn’t convinced that New York was ready for this street food of the gods until she ducked into her favorite porchetta stand near the train station in Rome at 8 a.m. “The place looked like it had been there for 120 years,” she says. A train conductor sat calmly eating sliced tomatoes and anchovies and drinking a glass of white wine. “See,” she said to herself — “it can be done.”

Meredith Hoffman At Porchetta, the roasting meat is rubbed with a mixture of rosemary, sage, garlic, salt, and wild fennel pollen. The resulting aroma “would make Proust weep.”

Sara realized that she could fit neither the whole animal nor an oven large enough to roast it in her East Village hole-in-the-wall, so she roasts only the loin. She dispenses with the innards, and instead rubs on the flesh a mixture of rosemary, sage, garlic, salt, and — “the one ingredient without which it can’t be considered porchetta”— wild fennel pollen, which is to say the dried petals of the wild fennel flower. The she roasts it at a low temperature for six hours.

Porchetta has an aroma that would make Proust weep. The restaurant’s tiny interior concentrates that smell into a dense fug of roasted pork fat which you seem to actually taste in the back of your mouth; if you walk inside on an ice-cold day it practically knocks you over. Sara serves the pork on a ciabatta roll which soaks up the fat. The sequence of flavors is thus: crunchy bread, liquefied fat, crackling fat, pork. There’s no question that the best part is the thick, crispy slab of belly, which makes a noise like a potato chip when you bite into it and then delivers to the palate the sinful bliss of smoky, slow-roasted, pork-flavored fat. It just doesn’t get much better.

Sara is aware of the vegetarian proclivities of the neighborhood, and so offers weekly soups, a mozzarella sandwich, and “beans and greens” on the side. To dine thus at Porchetta, without the pork, is roughly equivalent to reading Playboy for the journalism. Still, you can absorb second-hand meat just by inhaling.

Porchetta, 110 East Seventh Street, 212-777-2151. www.porchettanyc.com