“Some people come for the food, some people come for the story,” says Asma Khan, in a quiet moment at her new restaurant, Darjeeling Express, near London’s Carnaby Street. The food is from the streets and homes of Kolkata, with the occasional trip to Hyderabad and Darjeeling; the story is that it’s cooked by a team of women with no former professional kitchen experience.

Khan, unfailingly described as “a force” by everyone who meets her, is tired but happy: Darjeeling Express has taken some time to come together. While she was studying for a PhD in constitutional law, Khan would see Indian nannies at her children’s school in South Kensington, “working for English or French families – never Indian”. She’d moved to the UK in 1991, and knew how lonely it could be, and how much she missed the food of her own family. So she invited the nannies round to eat. They were from different regions, religions and classes, spoke different languages, but sang the same Bollywood songs in the kitchen. When she handed in her PhD in 2012, Khan decided, at 43, that what she really wanted to do was cook, so began a supper club in her home featuring the Mughlai cuisine she’d grown up with in India, helped by her friends. “They would just turn up, they wanted to help cook,” she says of her army of nannies. Khan believes cooking can be a way to provide stability for those whose lives have been uprooted. “All these women lived lives unfulfilled. And always this feeling: ‘You are nobody, you have nobody, you don’t belong.’”

Khan is from an upper-class family; her mother is Bengali, her father Rajput. She says she was loved, yet in India, as a girl, it’s hard not to feel you’re less valued than a boy. She also realised her privilege had brought opportunity and education but there were many women, especially immigrants, who never had the same options. “Doors have not just to be opened, but held open,” she says, “and people helped through.”

In 2015, Darjeeling Express briefly moved to The Sun & 13 Cantons pub, Khan working alongside head chef Asha Pradhan, 44. Pradhan’s father was a caretaker at one of the Khan family homes in India and in 2003 she moved to the UK to help Asma with her house and family. They were supported in the pub by five other women on their days off from their jobs as nannies and carers. Now, gradually, the part-timers are becoming full-time, and Khan has realised her dream to have an all-female team of chefs (the restaurant’s kitchen porter and majority of the waiters are men).

Many of the chefs were sending part of their wages to family in India, as well as supporting families here, so Khan, who says she pays her cooks the same rate as she pays herself, didn’t let them serve notice on their old jobs until the Carnaby Street site had opened. And to differentiate between the supper club and the restaurant, everyone swapped their salwar kameez for whites. “That symbolism matters.”

When I visit, it’s the first day as full-time professional chefs for two of the team. Shanta Awale, 49, moved from Delhi 13 years ago. One of the original supper-club team, she now excels at making roti. “I was a nanny and my hobby was cooking,” she says. “Today, I’m a chef.”

Anita Gurung, 41, is a more recent recruit: she met Khan five weeks previously, introduced by her mother-in-law, who also works at the restaurant. Like her fellow nascent chefs, Gurung, who is from Nepal but has lived in the UK for 17 years, seems unfazed by a busy kitchen. “It’s easy,” she says. “I like to eat, so I’m interested.” Khan isn’t sure whether her staff have adapted to working in a full-time kitchen so well because they’re easygoing or because they’re accustomed to tough jobs. Before preparing papri chat and frying the lightest onion pakoras in the city, Gurung worked in a care home, bathing and dressing the elderly.

Prior to Darjeeling Express opening, Khan spent a day at Tredwells with chef Chantelle Nicholson, who she had met at a food-industry event earlier in the year. Nicholson had been charmed by Khan – everyone is – and offered her help, mostly with the logistical challenges facing new restaurateurs. “They’ve got that down,” says Nicholson. “I was just helping make their lives easier, to make sure they could get more enjoyment out of work.”

Khan is proud of her team, that they’ve all taken risks on a new job, that once they were nervous but now happily chat to customers at the pass. “I want to see these women doing something else,” Khan says. She wants Darjeeling Express to be a place women learn new skills, then leave for other jobs – maybe start their own businesses. “We’re going to take more women in, to give more people more help and more control of their lives.”

As a new trainee finishes her shift, Khan calls out her thanks. “She’s never worked before this,” says Khan. “She has two kids but told her husband he must look after them. I pay her more than the other women; everyone knows that.” Khan explains that, in a few years’ time, the woman’s children will realise she has done something amazing, but right now they’re still adjusting to days without their mother, so she gets a little extra to buy something for her family every day.

“Darjeeling Express has allowed these women to have roots,” Khan continues. “They’ve grown, in dignity, in their family, in the way they negotiate with their sons and husbands, in who they will be their whole lives. There’s no going back.”

Darjeeling Express, Top Floor, Kingly Court, London W1B 5PW; darjeeling-express.com