CAMBRIDGE - Director David Gelb is windswept. He’s just come in from a walk through Harvard Square wearing ripped jeans, a plaid shirt, and a black hoodie to ward off the cold. He is in town from Los Angeles to talk about his new film, “Jiro Dreams of Sushi,’’ a documentary about legendary Japanese sushi chef Jiro Ono.
Gelb’s previous projects include the short film “King of Central Park’’ and a rockumentary about the band The Hold Steady. “Jiro’’ opens April 6 in the Boston area.
Gelb, 28, a graduate of the University of Southern California School of Cinematic Arts, grew up eating sushi: He would accompany his father, Peter Gelb, now the general manager at the Metropolitan Opera, on business trips to Tokyo. But few people make sushi like Ono does. In his 80s, the chef is proprietor of Sukiyabashi Jiro, a 10-seat restaurant located in a Tokyo subway station. The restaurant has been granted three Michelin stars. Yet even after decades of work, Ono tells us in the film, he hasn’t achieved perfection. With his exacting standards, it is possible perfection doesn’t exist. The chef is a shokunin, the Japanese term for a true craftsman. He has passed his trade along to his sons: The eldest, whose skill some say equals Ono’s, labors in his father’s shadow at Sukiyabashi Jiro. He will one day take over the business. The youngest is making his own way at a second branch of the restaurant.
Gelb spoke with the Globe about getting to know the master, the meaning of craft and family, and what goes into a truly great piece of sushi.
Q. “Jiro Dreams of Sushi’’ is a story about food, family, and the artist’s life. What initially drew you to your subject?
A. I wanted to make it my job to eat the best sushi in the world and meet the best sushi chefs. My two passions are sushi and filmmaking. As Jiro says, you have to do what you love.
Q. Tell us a bit about your filmmaking process.
A. I borrowed money from my dad and my grandparents and other members of my family. I went out [in 2010] with a bunch of camera equipment, just me and my translator, who doubled as my camera assistant. I didn’t know what I was going to get. I didn’t always know exactly what I was shooting [due to the language gap]. What I thought was a profound discussion about sea urchin would turn out to be about a baseball game. I’d go in every day and follow [the chefs] to the fish market. I’d have breakfast with them every morning and integrate myself as unobtrusively as possible into their everyday routine. They eventually forgot I was there.
Q. You give viewers insight into a master sushi chef’s professional life: the relationships with purveyors, the attention to detail, the micromanaging of staff members, including Ono’s oldest son, Yoshikazu, his second in command and likely successor. You also let us into Ono’s personal life.
A. It’s as if there are two Jiros. Sushi chef Jiro doesn’t say a word behind the sushi bar. His staff views him with reverence and fear. Once service is over and he is able to relax, he has a great sense of humor. He has a great relationship with his sons. Jiro didn’t have a family growing up and had to leave home at 7. He grew up in the Depression and they couldn’t support him, so he became an apprentice. He wants to have the family he didn’t have, to be the father for his sons he didn’t have.
Q. On one level, this film is sushi porn: shot after glorious shot of beautiful, mouthwatering sushi. Is this primarily a film for food lovers, or does it have wider appeal?
A. I like to think [it’s for] anyone who loves cinema and/or food. The reactions have been really interesting and quite humbling. People who don’t even eat sushi find something to enjoy in the movie. It’s about more than sushi: family, life, hard work, and loving your work. People want that in their lives. If you are going to do something every day, find a way to enjoy and be passionate about it. It’s also a family story about living in the shadow of your father. I think a lot of people can identify with that.
Q. What does Ono’s work tell us about Japanese culture?
A. Originally, I wanted to make a film about four or five different sushi chefs. All I needed was Jiro. From the perspective of this master and artist, so much about Japanese culture comes through. He’s the living embodiment of the Japanese craftsman’s lifestyle, the way of the shokunin. You work at a single trade, and that’s your life. Your goal is to keep doing better and better work. There’s this focus on specialization and mastering what seems like a simple task.
Q. The sustainability of seafood is an increasing concern, frequently discussed in this country when the subject of sushi comes up. Is it something Ono and other top sushi chefs in Japan think about?
A. Jiro-san and Yoshikazu-san are very concerned about it, specifically the overfishing of tuna. If people ate sushi less often and treated it as the special occasion it is, maybe it wouldn’t be a problem. But people are eating it every day. This is a delicacy and should be treated as such. It’s not something you should stuff your gullet with. Artisans are very concerned about it. There are some very big sushi chains in Japan and China and other countries that are somewhat reckless and serving massive quantities of endangered fish. They are pulling them out of the water in a very unsustainable way. Jiro insists on using only fish that’s line caught.
Q. What about Ono’s brand of sushi artistry? Is it sustainable?
A. It’s an uphill battle, especially for Yoshikazu. He is in the shadow of his father, the greatest legend of sushi. He has to be twice as good as his father. At the same time, it’s hard to find dedicated staff. The quality of the ingredients themselves is in decline, and prices are going way up because of the explosion in popularity of sushi all over the world. Demand is so high. Plus, the  earthquake wiped out entire fishing towns. It was a terrible tragedy, and it’s very challenging. The economy is horrible in Japan. People are very anxious about nuclear disaster and concerned about radiation [after accidents caused by the tsunami]. People are not in the mood to spend $300 on a sushi meal when they feel uncertainty and anxiety. But Yoshikazu is an incredibly dedicated, passionate guy, and he’s not going to quit.
Q. What went through your mind the first time you ate at Sukiyabashi Jiro?
A. The first thing that struck me was how delicious the rice was. I had never eaten sushi where the rice was so good and did so much to bring out the flavor of the fish. The combination of the rice and the soy sauce and the wasabi - the balance and care Jiro puts into it - makes it so you taste the fish the way you’ve never tasted it before. It’s incredibly delicious. It’s like going to a sushi temple. It’s so quiet, and he has such an austere presence. It’s a holy experience.
Q. What will your next project be? Maybe a documentary about ramen?
A. I’m working on a script with one of my good friends. It’s a murder mystery movie. I’m going to try something completely different. I don’t necessarily see myself as a documentary filmmaker, just a filmmaker. This was an opportunity to tell a story about sushi and a great man. I don’t know if I will make another documentary. I don’t know if I’m as passionate about anything else as I am about sushi and Jiro.