Back in 2007 Indian-American filmmaker Ritesh Batra had interacted with Mumbai's dabbawallas for a couple of weeks while trying to make a documentary about them, but instead ended up making The Lunchbox.
"I wanted to find personal stories from among them. Instead we became friends and they started telling stories about the housewives they would pick up lunchboxes from," Batra told IANS in a phone interview.
"I got more interested in that. So I abandoned the documentary and started writing this," said the director, who has won the Best Debut Director prize at the prestigious 2014 FilmFare Awards for the film.
That was the genesis of the film set to release in New York and Los Angeles on Friday after a stellar run at the world's top film festivals including Cannes, Toronto, and Sundance where it met with rave reviews.
It then opens on March 7 in San Francisco, Washington DC, Chicago and other major US cities.
Batra never anticipated that the film would take both India and the West by storm.
"You are just trying to be honest to every moment of the film," he said. "It's hard enough to make a film. To anticipate what it's going to do later is just impossible."
The story revolves around Ila, a young middle class Mumbai housewife, trying to win back her husband's affections through his stomach and how a rare mistaken delivery in Mumbai's famously efficient dabba delivery system of lunchboxes, from homes to offices, connects her to a testy old widower (Irrfan Khan) through notes in the lunchbox.
"It was a very difficult role to cast," said Batra, who after lots of auditions spread over several months, settled on Nimrat Kaur, a relatively unknown actress who had earlier appeared in a couple of TV commercials in India.
Batra met Nimrat after seeing a couple of her plays at the recommendation of his casting director. "I had a great instinct about her, and when I met her the instinct grew stronger."
And Nimrat turned out to be "just a great great fit for the part. She really inhabited the part," said the director, who grew up in Mumbai and lives in New York. "I am really glad that we found her."
For the lead character of Saajan and his office colleague Shaikh, "I always had Irrfan and Nawazuddin Siddique in mind and I was thrilled when they came on board," he said.
Nawazuddin's character was always part of the screenplay, Batra said, but "He just became more and more important as I kept writing."
As for his technical crew "everything was sort of an educated choice to achieve a specific objective." he said.
Except for the cinematographer(Michael Simmonds)and the editor, largely the crew is from Bombay, "because there is a huge thriving industry here".
"It was important for me have the cinematographer from New York because he can see things that I can't see being from here. So it was very important to have a foreign eye."
"The editor (John Lyons) is someone I trust and always wanted to work with."
Batra has no immediate plans for a new film. With "The Lunchbox" set to release in US then in Hong Kong, Israel, UK,
Japan, and Australia "I have a lot of commitments to the film for the next few months - lots of travelling."