Tetsuya Wakuda strides straight past the “No Public Entry” sign on the auction floor of Sydney’s fish markets and plunges a finger into the notched tail of a shining, steel-gray tuna.

“Good color, not enough oil,” he says, shaking his head. He sets off at a near run across the briny floor until the gleam of a thousand tiny, luminous eyes pulls him up abruptly. The chef skids to a stop and sinks his hand, forearm deep, among the elastic little bodies of baby squid. “These!” he says, his round face wreathed in a smile of ecstasy. “These, I love!”

For an hour, Australia’s finest chef barges into cool rooms, steps behind counters, and peers into plastic tubs containing other restaurateurs’ orders. No doors are closed to him here. At 7 a.m., clad in a polo shirt, he is just as much at home among rubber-booted fishmongers as he will be at 7 p.m., immaculate in chef’s whites, greeting the Blahnik-shod clientele that has waited a month to get a table at his restaurant.

Tetsuya, who can’t bear to have the word fusion applied to his food—“confusion, that usually means”—is, himself, a fusion of the two very different cultures that have formed him. He can be matey and informal, calling himself “a terrible shit-stirrer” and cracking jokes with an Aussie’s irreverence toward sacred cows of all kinds. At other times, he projects a quietly centered Japanese reserve and speaks unselfconsciously of the importance of honorable behavior and commitment.

The first time we meet, it is late afternoon in the spacious bar of his restaurant, and he greets me with the vestige of a formal bow that his 20 years in Sydney have not yet quite eradicated. Outside, early-autumn light plays on camellias and water-splashed rocks in the generous garden that belies our location, tucked amid the city’s skyscrapers. Across the room, a wine merchant is pitching Margaret River Shiraz to an underwhelmed sommelier, and I have to lean forward to catch the soft-spoken chef’s words.

He is talking about the northern Japanese home-style cooking he grew up with in the city of Hamamatsu, on Honshu, Japan’s largest island. “I always liked a variety of food on the table. If there weren’t many dishes, I would say to my mother, ‘Is that all?’ And then I’d get smacked.” Because his parents were busy and fairly affluent—his father ran a fabric-sizing factory and his mother also worked in business—there were frequent evening outings for sushi or tempura, weekend excursions to Tokyo, and occasional treats at expensive restaurants to reward a good school report card. “I loved eating, was always hungry,” he recalls. But he never thought of becoming a chef: “Cooking was a girl’s thing.”

What he did know was that he would live overseas. “I was fascinated by foreigners, with other countries rather than my own.” At 22, he dropped out of business school, had a blazing row with his parents, and headed to Australia “because it was the easiest Western place I could get to.” He arrived with a single Adidas bag and hardly any English. Within a year, after stints as a dishwasher and prep cook, he met the patriarch of modern Australian cooking, Tony Bilson, a chef steeped in French technique but evangelical about Australia’s diverse produce. Bilson was looking for someone to do sushi. “I think he just assumed that because I was Japanese I would know it,” Tetsuya says.

He didn’t; and so, having accepted the job, he spent a day watching one of Sydney’s best sushi chefs at work. “I thought, he’s been doing that, and only that, for thirty years. I can’t match him. I’ll have to do something different.”

As he explains how he made things up as he went along, his hands fly, slinging imaginary ingredients. “What is it, sushi? What is it for? Wasabi, vinegar—these give appetite, lift palate. So, if you want to lift appetite, serve it first. But lighter, more delicate. What if you liquidize the rice? What if you make the wasabi a jelly?” And what if you serve the silky-sharp result in a Martini glass as the first of 14 small courses that are all just as original and unexpected? You might end up with one of the most award-garlanded restaurants in Australia.

Tetsuya credits Bilson with teaching him European technique and then encouraging him to put “my something in it.” Tetsuya and Bilson’s headwaiter started their own venture about a year later, and in 1989, Tetsuya struck out on his own, in a tiny unmarked shopfront wedged between a discount fruit barn and a charity clothing store in the Sydney suburb of Rozelle. Soon, the modest place was booked weeks ahead, and Tetsuya had to rent neighboring houses just to provide food and wine storage and “somewhere to do the next day’s braising.”

When the vast premises that had once housed the Suntory whiskey company’s early venture into upscale Japanese food came onto the market two years ago, Tetsuya didn’t hesitate. He wanted the space, but not simply for more tables. The new premises have 15 times the square footage of the old place, but Tetsuya has less than doubled the number of covers, to 90 from 55. “I wanted to realize my dream of what a great restaurant should have”—a spacious, private feel to each table, room for a 40,000-bottle wine cellar, a test kitchen where recipes can be tweaked without interrupting the flow of service, a chef’s private dining room with an open-plan kitchen where Tetsuya can cook for his friends. So unconcerned was he with the business logistics of a downtown restaurant that would essentially spurn the lunch crowd—Tetsuya’s offers lunch only on Friday and Saturday—that he fell asleep during a crucial loan meeting with his bankers. “My accountant says I actually snored,” he recalls.