The first rule of Japanese omakase is don't be late. Because everyone starts the same menu at once, the sushi master doesn't care if your Uber should have taken the tunnel. There's a bit to get through and food will be served on time, even if you're not.

We're exactly 12 minutes late to Gaku, a cosy hole-in-the-wall near St Vincent's Hospital, and our first course is already sitting on the red gum counter. It's a real cornucopia, too: delicious abalone in a buttery sauce made from its own liver; capsicum mousse brighter and more orange than post-mix Fanta; wagyu bresaola; pickled octopus and slivers of gently fried Murray cod marinated in vinegar.

Ornate trays are cleared and we're straight into the chawan-mushi, a little earthenware pot steaming with just-set egg custard and fleshy spanner crab, sweet and heady with the scent of truffles. Hang on a second, we haven't even looked at the drinks list yet! I bloody told our driver he should have taken the Cross City.

When Gaku opened in 2018, it quickly gained a legion of fans for limited-edition ramens at lunch and small, luxe plates in the evening. In September, owner-chefs Harunobu Inukai and Shimon Hanakura ditched the a la carte offering to go full omakase: that multi-course Japanese format that often focuses on raw fish and rice.

I could write about a different omakase every second week, such is their growing popularity in Sydney. Some of the new ones could well be cash grabs: you can charge astronomical prices while keeping staff and rent down since most omakases only seat a dozen or so diners. But many are also run by chefs who dream of sharp knives and pristine produce, and live to provide their guests with the most enjoyable time possible.

Inukai and Hanakura are very much the latter type, with ambitions to create a new style of omakase they call "Australian kaiseki", which is focused on detailed seasonal creations rather than straight-up sushi. The second rule of omakase is that you only speak in hushed tones, but there's none of that muted reverence at Gaku; "Australian kaiseki" also means "Let's party!"

"Everybody, wave hello to Charlie," instructs Inukai, holding up the carapace of a market-fresh lobster. "We're going to poach him in butter for our next course." Hi, Charlie; bye, Charlie. You were a good lobster that died a noble death to be served as meaty hunks in a vivid saffron soup built on individual broths of fish, mussels, pipis and kelp, and emulsified with butter.

"If I win Powerball, I'm going to buy a hundred Charlies!" hollers a bloke a few bar stools down. "Hear! Hear!" says a couple to our right, clinking glasses with the chefs and offering my wife some of their 2017 Savaterre Shiraz ($180 a bottle) from Beechworth.

Charlie's saffron soup is based on a recipe Japanese-born Inukai learnt in France before moving to Australia and working alongside the great Tony Bilson at Ampersand in Cockle Bay. During service, he wears one of Bilson's signature bow ties, gifted by the late chef's family, and is every bit the master of sauces and stocks his mentor was.

Meanwhile, former Aria chef Hanakura works with a furrowed brow to festoon an ice block with sashimi of kombu-marinated flounder, scallop and blue-veined paradise prawn. Later, caviar and gold leaf crown a "sea treasure" ball covered in spindly bits of spring roll pastry and filled with tightly bound scallop and prawn mousse – complete bliss presented in a wooden birdcage because a bit of kitsch never hurt anyone.

Across 10 courses, the only item I don't want to eat immediately again is the foie gras-filled monaka, a biscuity, shell-type thing with all the texture and excitement of a communion wafer. And while the wagyu is uncompromisingly delicious – charcoal grilled and beautifully marbled – it'd be nice if the wine list featured a reasonably priced red by the glass to drink alongside it. The cheapest option is a $32 pour of Beaujolais – after that you're looking at a 2020 Jean-Francois Ganevat poulsard from Jura for $70 a glass.

At $280 per person, Gaku is far from a cheap night out, but then Yoshii's Omakase at Crown is $350, and a joint called Oborozuki has just opened at Circular Quay that charges $450 for teppanyaki.

You're paying for high-end produce and fine technique here at Gaku, but you're also receiving humour, warmth and grace. With all that in mind, maybe it's actually a bargain. We finish with whisky and toast the kitchen. To Australian kaiseki. To Hanakura. To Inukai. To Charlie.

Vibe: Up-close omakase party

Go-to dish: Hassun tray (as part of a set menu)

Drinks: Short list of natural wines, sake, sochu, cocktails, beer and whisky

Cost: 10-course tasting menu, $280, excluding drinks

This review was originally published in Good Weekend magazine