When chef Koichi Minamishima accepted three hats for his eponymous Richmond sushi-ya at the recent Good Food Guide Awards, no one doubted the restaurant deserved it. But Minamishima-san might have, 20 years ago.

Then Boeing Cho, armed with a tiny photograph, was collecting him "bewildered, with his big suitcase" at Melbourne airport, to begin work as a chef at Kenzan, where Minamishima stayed for the next 15 years.

How many of Melbourne's great Japanese chefs have trod that path? It's a lot: Kentaro Usami, ex-Kappo and Izakaya Den; Shigeo Yoshihara of Tempura Hajime; Komeyui's Motomu Kumano, and Yoshiki Tano of Yu-u. All sharpened their knives and skills at 38-year-old Kenzan before striking out alone.

Kenzan is often accused of remaining unchanged in its almost four decade rule. And praised on the same account.

Cho, who began as a busboy more than 30 years ago and has been an owner for two decades, thinks it isn't true. But both sides have a point.

To untrained eyes, the room appears to have stayed steady, but it has been renovated four times. Tables were once inset with grills for the shabu shabu hot pots and regularly caught alight. There were once three tatami rooms. Now there are two. And the 10-seat sushi bar has been upped to 12.

Waitresses, now in simple maroon wraps, once wore full kimonos but "they required half an hour to dress and we were too busy", says Cho, who also remembers when people would leave their shoes outside the restaurant instead of the tatami rooms. Many got nicked.

The menu, always proudly broad spectrum, shows impressively high standard across its sushi, and hot and cold dish offerings. It might appear largely unchanged but that's more a reflection of the timelessness of the dishes.

The chawan mushi, a steamed egg and dashi custard concealing seafood, is a Melbourne benchmark, just barely holding it together. Before salted and grilled kingfish collars were everywhere, it was on the daily specials list (still the best way to order), in all its sticky-fleshed, crisp-skinned glory.

The sushi offering has increased as availability has improved and audience demand increased. Salmon and tuna were once the primary push. Clients now call to check what's on. There are probably 15 fish, both local and imported from Tokyo, to be palmed over correctly textured rice.

Today it's the fattiest part of alfonsino, gently torched to hit the buttery marshmallow notes. Scored whiting gets a sweet miso and bright shiso leaf boost. Our otoro (tuna belly) is a glistening slice of ocean butter, and gingery scampi clings to your tongue in raw, sticky glory.

That's Kenzan's ace in the hole. Not that it hasn't changed what it serves or how it looks, but that it has kept up a totally consistent standard on every front. Kenzan runs with the pack, as here and now today as ever. Is the wine cutting edge? Maybe not, but why aren't you ordering Kirin Ichiban longnecks and stone vessels of curious sakes anyway?

Cho is retiring next year, but Kaz Murayama (the son of an original founder) and Yuki Munehiro plan to stay the course. Apparently, Kenzan has never been busier – one regular comes four to five times a week, and while Cho won't spill on which celebrities frequent he says it's "everyone with money". You can't argue with that. Don't try.

Address 45 Collins Street, Collins Place, Melbourne, 03 9654 8933, kenzan.com.au

Signature dishes Sushi and sashimi; chawan mushi; anything from the daily specials.

Est 1981

Famous diners They will never, ever kiss and tell.