Avocado toast with a Japanese twist at Cool Mac cafe

Yes, Cool Mac in Kirribilli serves avocado on toast – but don't expect the drab version seen on uninspired cafe menus across Sydney. Here, chef Jun Okamatsu has cross-bred the familiar brunch staple with a Japanese dish, nasu dengaku (miso-glazed eggplant), and the result is worth your attention.

Cubes of eggplant – deep-fried to the point of caramelised sweetness – are jumbled on top of toast with avocado and cucumber, and garnished with shredded leek, seaweed and chilli threads. What gives this dish proper lift-off is the syrupy sauce drizzled throughout: sweet and ultra-savoury drips of miso boosted with sake, mirin, sesame oil and a touch of sugar. This avocado on toast remix is so good, it might compel you to give up any shot of housing affordability.

As you might guess, Cool Mac offers a not-so-standard menu. Its been a familiar sight on this quiet Kirribilli strip for years, but its current guise as a Japanese-inspired cafe is a more recent update. For owner Eugene Leung, this incarnation has required some getting used to. When diners initially turned up asking for fried eggs for breakfast, they weren't quite ready to learn that only "onsen eggs" were available. In fact, they often enquired what exactly was an onsen egg?

"That was the first question that people would ask, after we gave them the menu," Leung says. "And it still is." Named after Japan's hot springs, legend has it that these eggs were originally cooked in the steamy spa water – guests would drop them into the hot baths and return hours later to find the slow-cooked, custardy eggs ready to eat. At Cool Mac, they're made in a more conventional kitchen, far away from bathing tourists, and the dish is served with breakfast staples like bacon, avocado and mushrooms.

The menu takes you on other express trips across Japan. For instance, the Mayumi breakfast set includes a clear soup made with white soy, bonito and seaweed broth – its delicate flavours are a Kyoto specialty.

Then there's the taco rice with wagyu mince, a popular dish that arrives via Okinawa (it was originally created by locals catering to the tastes of American troops stationed on the Japanese island – apparently it was a way to maximise the measly taco rations they received). You don't have to be in the US military to enjoy Cool Mac's version: it's got a garlicky, spicy kick, thanks to the free-spirited squiggles of sriracha chilli sauce and home-made aioli on top and densely packed combination of avocado, lettuce, tomato and miso-braised mince, all crowned with a perfectly fried egg.

If you're lucky enough to get here when a ramen special is on, order it. Cool Mac's version of the noodles, flavoured with pork-intense tonkotsu broth, is enough of a Sydney standout that the crew has been invited to appear at the Slurpfest: Ramen Masters series that Newtown's Rising Sun Workshop cafe and food blogger Raff de Leon are currently running. When that program's line-up also includes ramen-making royalty such as Gumshara's Mori Higashida and Chaco Bar's Keita Abe, you know that Cool Mac's offerings must be a contender for the city's best.

The cafe is aptly stocked with souvenirs from Japan – some that have tested Leung's baggage limits. Shiny coffee cans sit on one shelf, ranging in mood from the blazing red Wonda Morning Shot (a brand endorsed by 92-member J-pop girl group, AKB48) to the brooding Pokka Coffee that soberly announces its "since 1972" inception. These were smuggled back to Sydney by Leung – only for him to discover that lugging kilos of coffee cans was entirely unnecessary. These brands are easily available at local Asian groceries. He didn't make the same muscle-straining mistake with the Japanese coffee-vending machine that sits in the corner: that was simply shipped back to Australia.

Outside, young couples sit at tables, drinking iced lattes and enjoying orders that seem well-intentioned and healthy (aburi salmon salad) and unapologetically not (grilled cheese melts topped with large rashers of bacon tempura). When they head to the counter, they may notice that Cool Mac also doubles as a gallery. The current black-and-white artworks of breaking waves are by Daniel French-Wollen, and there was a recent show inspired by Studio Ghibli films. Leung isn't sure how the cafe space will work for an upcoming jewellery exhibition. "I'm interested to see how it's going to play out."

When he first began this program, he asked his mother for suggested artists to show – she's a National Art School graduate. So has her work been displayed here? Leung thinks her edgy installations might be "a bit too cool for this place". She has, however, contributed something else: the cafe's name. Cool Mac refers to an iced double-shot macchiato Leung used to serve. You can't request it any more, but the eatery is full of other good things worth ordering.

Main attraction: Cool Mac's inspired twist on Japanese food – you could imagine a gem like this in the quiet back streets of suburban Tokyo.

Must try: It's a toss-up between the dengaku toast and taco rice.

Insta-worthy dish: The Mayumi breakfast set: a wooden tray elegantly topped with multiple dishes, from impressive Hainan tofu to agedashi mushroom and eggplant.

Next up: Coming dinners that showcase Cool Mac's love of ramen. "It'll give people the opportunity to try our ramen when they're usually stuck at work," owner Eugene Leung says.

Rating: Four stars (out of five)