The door opens at Majoria’s Commerce Restaurant, and before it can shut, Jean Robinson and Cassandra Brown are hailing the new arrivals from the deli counter across the room, urging them to step on up, pitching the daily special and, if they look like out-of-towners, describing the house standards.

“Red beans and rice, muffuletta, po-boys, the salads are over here, there’s the seafood platter,” Brown calls out.

It’s fast, it’s crowded, it’s loud, and first-time visitors sometimes seem a little puzzled as they step in from the CBD sidewalk, perhaps surprised to see a downtown diner that looks so much like a vintage time capsule moving so briskly to the here-and-now lunch rush.

But when regulars walk in, sometimes they don’t even order. They just take one of the six swivel stools at the short diner counter or plant themselves at a Formica table and wait for the diminutive Evenia “Vanna” Isaac to shuffle through the crowded room and deliver their standing orders.

“Here you go, baby, enjoy your lunch,” she says invariably, barely audible over the din of Brown and Robinson greeting more customers.

The Commerce probably didn’t seem extraordinary when it opened in 1965 at the corner of Camp and Gravier streets, across from the former location of the Chamber of Commerce, its namesake.

But this month marks its 50th anniversary as a survivor. It’s part of a dwindling breed in the city’s rapidly-changing downtown, an eatery where the texture and ambience, the interplay of staff and regulars and the brusque affection built into the business of po-boys and plate lunches mixes old time Americana with something much closer to home.

“This is old school New Orleans. It has the feel of New Orleans. You don’t feel like you’re in some sterilized chain,” Jerry Strahan said while making his daily lunch visit to Commerce.

Strahan knows something about that. He’s the manager of Lucky Dogs, which keeps its fleet of wiener-shaped vending carts half a block away on Gravier Street. He’s been a Commerce regular since the mid-1980s.

“Commerce has a certain sense of character,” Strahan said. “So many things in New Orleans are gone, have disappeared. But this place still feels the same.”

It sounds the same, with the constant clunking ring of proprietor Brett Majoria working the ancient cash register. Good natured and soft-spoken, he’s always here, surveying the room from the till like a captain at the helm.

Over his shoulder, a plaque on the wall honors the memory of his late father, John “Chance” Majoria, with an epitaph of sorts that reads: “Women’s pet, the men’s regret, better known as Mr. Satisfaction … but better.”

“He had swagger. Let’s put it like that,” said his son.

He also had personality and a mix of thriftiness and ingenuity that all helped set the style of Commerce that endures today.

“He liked working with his hands. When something broke, you didn’t replace it, you took it apart and rebuilt it,” said Brett Majoria. “That’s why we still have all this old stuff.”

The son of Sicilian immigrants, John Majoria was part of the family that started Majoria Drugs and Majoria’s Grocery in Boutte. He got into the restaurant business with his childhood friend, Bruce Griffen, when they bought the now-long-gone downtown cafe Mumphrey’s on St. Charles Avenue. They then bought the Commerce Restaurant about a year after it opened. There was no question back then that New Orleans staples would be their bread and butter.

“We just stuck with what we knew,” Griffen said. “There were a lot places downtown doing the same thing, but that’s how people ate. There was a lot of business to go around for that kind of thing.”

A menu from 1965 lists oyster po-boys for 65 cents and veal stew for 85 cents. You could get a sardine po-boy or one filled with tongue and liver cheese.

Griffen recalls that basic lettuce and tomato salads came with one dressing option: mayonnaise. And the restaurant had gender-specific serving standards for its po-boys.

“If it was a man, they got theirs wrapped in paper. If a woman ordered one, it came on a paper tray,” he said.

Brett Majoria started working by his father’s side here after graduating college in 1992, and he took over not long before his death in 2013.

The long reach of family ties apply to others working here. Jean Robinson, for instance, has been making po-boys and serving up the red beans at Commerce since 1991, when she was brought into the fold by her mother, the late Jerrobean Bowens, who cooked at Commerce for 38 years.

“We’re pleasurable people, and this is a pleasurable place,” Robinson said, describing her approach to counter service. “We smile and joke with the customers. We don’t care where you’re from or what you’re doing. We’re here to make sure you get a good meal, and people like that.”

Like the other longtime employees here, Robinson prides herself in knowing her regulars’ orders, how they like their sandwiches, when they might be susceptible to a special. Those offerings saw a substantial change a few years back after Majoria himself adopted a very low-carb diet. He’s shed a lot of weight since, and the customized lunch dishes he asked his kitchen to whip up for him are now in regular rotation on the specials board.

It might be pork chops with spinach and egg one day, or a roasted turkey wing with smothered shrimp and okra or bacon-wrapped chicken with cabbage cooked in coconut oil. Regulars have worked them into their habits, too, between the po-boys and lasagna.

Other changes, though, are small scale and carefully considered. He started taking credit cards a few years back, but he dismisses any talk of replacing the burly old mechanical cash register.

“That’s history. That’s part of my father’s history and the history of this place,” Majoria said. “When I see it, I see him standing behind it. I can’t change that.”

Follow Ian McNulty on Twitter @IanMcNultyNOLA.