The film centers on Shira, an 18-year-old Hasidic girl who is thrilled about her forthcoming arranged marriage with a young man whom she has only briefly seen in a supermarket.
Tragedy strikes when Shira's older sister Esther dies giving birth, leaving the family crushed by grief.
Esther's husband Yochai is quickly pressed to remarry a widow in Belgium, but the girls' mother is desperate to keep her only grandchild in the country - and soon Shira is asked to step into her sister's shoes.
The film, set in the secluded Hasidic community living in secular Tel Aviv, offers a rare glimpse into the Orthodox way of life, its rigid customs and traditions, but also deals with the wider themes of relationships and family pressures.
According to the film's producer, it is "a Jane Austen of the Hasidic world."
"This community in Israel is very secluded and we see them in a kind of black and white way. This is a unique way to have a voice heard from the inside," the producer, Assaf Amir, said at a press conference in Venice.
"Rama is a pioneer in that sense. She is the first woman from that world to make a film and I don't think there are any men making any," Amir said, comparing the movie to the novels of British literary great Austen.
"People don't know much about this world, so it's not a question of celebration or criticism, it's a window into this world," said New York-born Burshtein, who grew up in a secular family but became ultra-Orthodox shortly after graduating.
"I love this world, I come from it, I chose it, I was not born in it. But I think we hear many voices (in the film), I think it's open," she told reporters.
Burshtein said she had based the film on a real-life story she heard at a wedding. "I was fascinated. I was asking myself how is that? Is it about feelings? Is it about family? Is it about duty?" she said.
"She is a child but she is becoming a woman as the movie goes along. The story is about a girl becoming a woman in the oddest circumstances," she said.
The tension between tradition-bound lives and raw emotions welling up is one of the highlights of the beautifully shot film.
Emotions and choices
Hadas Yaron, who is herself secular and plays the character of the young girl Shira, said: "It was a lot of work getting to know that world.
"It's all about emotions and choices and what leads you (to) do what you do. Shira is different from me because she's not familiar with all these feelings that she's experiencing for the first time," she said.
Irit Sheleg, who plays Shira's mother in the film, said the story highlights the crucial roles of women: "In the film the people who do business are the women. They are very strong, very dominant."
Burshtein has spent more than a decade teaching and making cinema for the Orthodox Jewish community, some of them for women only as Hasidic men are barred from viewing women on the big screen.
She is one of 21 female directors at the Venice film festival this year, and one of the four competing for the top Golden Lion prize.
The heavy female presence on the Lido waterfront, including Saudi Arabia's first woman filmmaker, is in stark contrast to this year's Cannes festival, where the absence of female directors in the main competition led to accusations of sexism in the French press and further afield.
Film critics have branded Venice's 69th edition a "pink festival" but artistic director Alberto Barbera, who took over the helm of the world's oldest movie showcase this year, said this was not intentional.
"I don't like the idea of Indian reserves or pink quotas. It's just a sign that women's creativity is very present in a world that for decades has been dominated by men," he told reporters at the opening of the festival last week.
Reuters and AFP contributed to this report