During her 25 years as one of Boston’s most acclaimed chefs and one of the most renowned restaurateurs in the country, Barbara Lynch has told and retold her origin story: how she rose above her poor and violent childhood in South Boston, and fought sexism as a line cook to reach the top of her profession.

So on March 15, when she gathered two dozen employees of Menton, the most prestigious of her seven establishments, for a meeting after dinner service, they were hoping for support and inspiration.

All were exhausted and grief-stricken. Two months earlier, their head chef, Rye Crofter, had died of a fentanyl overdose. That morning, they’d learned that a young line cook who Mr. Crofter had mentored had died in the same way.

“Talk to me,” Ms. Lynch told her staff. “Tell me what’s going on. Be honest.”

But instead of support, Ms. Lynch — who several employees said had been drinking beforehand in the restaurant’s private dining room — delivered outrage and self-pity, in an expletive-laced confrontation that one employee recorded and shared with The New York Times.

When Tim Dearing, who had taken over as the restaurant’s lead chef, challenged her by pointing out that she hadn’t visited the kitchen after Mr. Crofter died, she fired him on the spot. When he responded that he would “drag” her — damage her reputation — Ms. Lynch threatened to push his head through a window.

“I’m not going to stand for it,” she told the group, adding. “I don’t want negativity in my life.” She instructed them to show up the next day to learn whether they would keep their jobs. All eight of Mr. Crofter’s remaining kitchen crew resigned within days.

Twenty of Ms. Lynch’s former employees and more than a dozen veterans of Boston’s restaurant business have told The Times that her actions, while shocking, were not surprising. For decades, they said, her alcohol abuse and verbal and physical aggressions inside the restaurants have been an open secret among hospitality workers.

In recent years, former employees said, the frequency of Ms. Lynch’s abusive outbursts and impulsive firings has increased, even as many chefs have improved workplace conditions since the start of the #MeToo movement. In her own dining rooms and bars, they said, she drinks heavily and has subjected employees to unwanted propositions and touching. Because Ms. Lynch is the majority owner of her restaurants, answerable only to investors, the former employees said they had no recourse except to go public with their grievances.

“She has always been protected from the consequences of her actions,” said Sara Hatanaka, a manager of B&G Oysters and the Butcher Shop from 2020 to 2022. “At some point, everyone has to be held accountable.”

In a statement on Wednesday, Ms. Lynch categorically denied the allegations. “I expressly reject the various false accusations lodged against me that I have behaved inappropriately with employees or crossed professional guideposts that are important to me,” she said.

Ms. Lynch said she “cannot put out all the fires that flare in this high stress environment and my very modest roots allow me to recognize that I’m far from being above reproach. I make personnel decisions that may rankle those who don’t measure up or don’t want to commit to true teamwork and service; perhaps some I should have removed sooner.

“I acknowledge that I am a creature of the alcohol-steeped hospitality and restaurant industry,” she added, “and I am committed to taking responsibility and working on myself.” But she said the accusations were “fantastical” and “seem designed to ‘take me down.’”

Since Ms. Lynch, 59, opened her first restaurant, No. 9 Park, in 1998, her success has seemed boundless, stretching beyond the culinary world. After her candid memoir, “Out of Line: A Life of Playing With Fire” was published in 2017, Time magazine named her one of the world’s most influential people. She has won accolades like Outstanding Restaurateur from the James Beard Foundation, an Amelia Earhart Award for pioneering women in Boston and an honorary degree from Northeastern University. On Saturday, she opened her first new restaurant in nearly a decade, the Rudder, near her home in Gloucester, Mass.

“Barbara Lynch helped Boston open its food horizons,” said Corby Kummer, the executive director of the Food and Society program at the Aspen Institute and a longtime food writer in Boston. Starting in the 1980s, he said, the city became a beacon for women chef-owners.

Ms. Lynch’s restaurants remain popular, her creativity and charisma still earn admiration, and many employees have had long tenures with her restaurant group, the Barbara Lynch Collective.

John George, who has been a server in Ms. Lynch’s restaurants for 23 years, attended the March staff meeting in his role as a captain at Menton. “Emotions were running high that night,” he said Wednesday, when the company made him available for comment. “But over the years she has been an incredible mentor, and given support and opportunities to so many employees.”

For years Ms. Lynch’s restaurant group flourished under a strong leadership team, the former employees said, but over time her behavior has become more erratic. And the sharp elbows and raw language that she once cultivated to succeed in a male-dominated field are no longer tolerated in many restaurants.

Michaela Horan, who is also from South Boston, said she had long admired Ms. Lynch’s fierceness and talent, and was flattered to be taken under the chef’s wing after she was hired as the manager of the Butcher Shop in August 2018.

But Ms. Horan said she was surprised to find that Ms. Lynch did little cooking and a lot of drinking. When she mixed the two, Ms. Horan and employees at other restaurants said, chaos ensued. On the occasions she spontaneously took charge of the kitchen while intoxicated, they said, Ms. Lynch sent out barely cooked chicken, threatened staff members with knives and threw away orders when she fell behind.

Ms. Horan said that one night in June 2021, when she allowed a table to order appetizers without committing to entrees, Ms. Lynch stormed up from the kitchen, repeatedly prodded her shoulder to get her attention and dragged her out from behind the bar in the crowded dining room. (An eyewitness confirmed the incident.) Ms. Horan resigned immediately.

“No one had ever put their hands on me before,” said Ms. Horan, who already had a decade of hospitality experience. “Once was enough.”

Drink, a craft-cocktail bar, was considered the best bar in the city to work in when it opened in 2008, overseen by the restaurant group’s wine director, Catherine Silirie, who won a James Beard award in 2012 and worked for the group until 2020.

Oscar Simoza was hired as head bartender to reopen Drink after the initial pandemic shutdown, in June 2021. “It was a high-profile job and a great brand,” he said.

But he said he was uncomfortable when Ms. Lynch showed up to drink at the bar, or to push her way behind it, touching employees on their groins and bottoms on the pretext of squeezing into the narrow space. At a time when the hospitality industry was supposed to be pulling together, he said, he was disgusted that she took advantage of her power over employees.

“I’m a 6-foot-5 guy, and I can take care of myself,” said Mr. Simoza, who left the job last year. “But we were all so vulnerable.”

One former Drink employee, speaking on the condition of anonymity because she feared retaliation, said that soon after she was hired, in early 2015, Ms. Lynch came behind her just as she straightened up from lifting wine bottles to the bar. She said Ms. Lynch told her they would make a good couple, then caressed her lower back and squeezed her bottom. If any guests had done that, the employee said, they would have been asked to leave.

Ms. Hatanaka said that for managers like her, staff turnover was a constant problem. Ms. Lynch’s unpredictability made it impossible to run a professional workplace or discipline certain workers. “We couldn’t write someone up if they were one of her favorites,” Ms. Hatanaka said. “Or deal with a complaint about a chef drinking in the kitchen.”

Michael Dudas, the group’s director of operations from 2021 until Ms. Lynch fired him last month, said he and other employees sometimes drove her home when they felt it was dangerous for her to drive. In 2017, Ms. Lynch was charged with driving while intoxicated, and agreed to give up her license for 60 days and complete an alcohol education program while on probation. Even during that probation, which was widely reported, Ms. Hatanaka said, Ms. Lynch came to Menton’s elegant Gold Bar and drank in front of customers.

On March 2, two former employees filed a class-action lawsuit against the restaurant group, alleging that tip money had been diverted from their paychecks when they returned to work after a pandemic furlough in May 2021. A spokesperson for the group has disputed the claim.

In her statement, Ms. Lynch pointed out that “early in the pandemic, we fed employees to help them through that time when all restaurants were closed. I have provided coverage for employees suffering from trauma and other challenges and I have mentored chefs that have gone on to national and international renown.”

The former employees said they had been reluctant to criticize Ms. Lynch because of her connections to powerful people in Boston. Stephen F. Lynch, a longtime congressman, is her first cousin. Tom O’Neill, a former lieutenant governor who now runs one of the city’s top lobbying and public relations firms, is an investor in No. 9 Park, which sits directly across from the Massachusetts State House and often hosts private breakfasts for politicians.

Pedro Fuentes, a former line cook at the Lynch restaurant Sportello, who grew up in nearby Chelsea, said that he and others believed that in Boston, there would be no consequences for Ms. Lynch’s leadership failures. “If you’re from here, you already know,” he said.

“The Lynches are to Southie what the Kennedys are to New England,” he said. “American royalty.”

The restaurant group’s big expansion occurred from 2008 to 2010, when it opened three new places including Menton, whose refined modernist French-Italian food put it on national top-10 lists; it was the first restaurant in Boston to join the international Relais & Châteaux group.

At that time, working between Ms. Lynch and the group’s more than 200 employees was a robust layer of management called the “top team,” which kept the company going.

But as the company expanded, many former employees said, Ms. Lynch seemed less interested in running it. The restaurants continued to attract top culinary talent like Colin Lynch (no relation to Ms. Lynch) and the “Top Chef” winner Kristen Kish, but Ms. Lynch spent more and more time at her home in Gloucester, 35 miles north of Boston. The Barbara Lynch Foundation, which she had started to promote healthy food for Boston schoolchildren, peaked in 2015 with over $100,000 in revenue from contributions, according to I.R.S. filings. But the foundation has reported zero income and expenditures every year since 2019.

By the time Boston restaurants reopened after the first pandemic wave in June 2020, Ms. Lynch had dismissed nearly all of her top team. Mr. Dudas, the group’s former director of operations, said that many of them had tried to persuade her to get treatment for her drinking problem, and that since then most of those roles have gone unfilled.

Servers at Menton last week said that Ms. Lynch had briefly returned to work in the kitchen after the Menton cooks left.

Felipe Goncalves, who oversaw the line cooks at Menton until the tense meeting with Ms. Lynch, said he had worked there for two years and had never met her; he knew her only as an absentee owner who sometimes passed through the kitchen while intoxicated. “I was there to learn from chef Rye,” Mr. Goncalves said, referring to Mr. Crofter.

When Mr. Crofter was hired in 2019, he and others said, he brought a modern aesthetic and skills like foraging and fermenting that attracted a new caliber of cooks. When he died in January, Ms. Lynch had just named him executive chef of all seven restaurants.

She said in her statement that the deaths of the two Menton cooks “was a personal tragedy for me. It is difficult to put that type of loss into words, and finding the strength to comfort the team in the aftermath of those losses was incredibly difficult. I’m human, and looking back, I wish I had the capacity to have handled it better as a leader and as a friend.”

Mr. Dearing, the chef who Ms. Lynch fired during the staff meeting, said that like many cooks, Mr. Crofter had battled addiction, but had not used drugs for nearly a decade.

“I came up like she did, getting kicked and having pans thrown at me,” Mr. Dearing said. “But we were trying to build a better culture there.”

Colleen Cronin contributed reporting from Boston.