When Quay became the first Sydney restaurant to charge $50 for a meat-based main, the city's lunch set was quick to recoil in horror. Now, little more than two decades later, a cauliflower with a price-tag of $57 barely causes diners to blink.

"We introduced the [$57] whole cauliflower in December and it's been really well received," says Nicola Somerville, general manager of Chiswick restaurant at the Art Gallery of New South Wales. A medium-sized cauliflower costs about $7 at most supermarkets.

"It's not like we just chop up a stalk of a cauliflower and serve it," says Somerville. "It's brined, twice-cooked, covered in harissa paste and served with a zucchini and pomegranate medley. The final result is so delicious that it reminds our guests there's room for more on their plate than meat."

The Woollahra outpost of Chiswick, co-owned by celebrity chef Matt Moran, is also offering a new $150 a person vegetarian feast in response to increased consumer demand for sustainable, plant-based food.

"There's definitely more plant-based food coming to our menus," says Moran. "It's what people want. People are more conscious of what they're eating."

Most of Chiswick's cauliflower eaters aren't vegetarian or vegan but they are reducing the proportion of meat in their meals.

"In the past, maybe two people would share a lamb shoulder," says Moran. "Now it's shared between four and they're ordering the cauliflower, maybe a fish dish and a lot more sides."

Moran farms livestock and is a committed meat eater but even he has a flexitarian approach.

"I have a couple of nights a week that I try to eat vegetarian," he says. "I actually roasted a whole cauliflower at home last night."

Plant-based dining ties into a key global trend for 2020 noted by digital agency Wunderman Thompson in its new Future 100 report.

"Consumers are pivoting towards a 'climate diet', consuming less meat and dairy and seeking environmentally friendly alternatives," it reads.

Tastewise, an Israeli start-up which uses artificial intelligence to forecast food trends, notes in its January 2020 report that 23 per cent more US consumers prioritise sustainable food choices than they did a year ago. It finds health is the primary driver for making food choices that happen to be more sustainable, however, such as eating more vegetables and less (or no) animal products. Being vegan and being a climate activist aren't necessarily the same thing.

"Eating mostly plant-based is a good start – red meat and dairy are the products with the most significant climate change impact," says Michalis Hadjikakou, lecturer in environmental science and management at Deakin University. "But minimising waste and excess consumption are also important."

Popular vegan foods - such as almonds and soy, depending on their source – can also have impacts in terms of deforestation, high water usage and food miles.

Entrepreneurs are flocking into the plant-based space, including Michael Fox, owner of Fable, a vegan food company which launched in Australia in December and is hanging its hopes on mushroom-based mock meat.

"Consumers want to eat products that have a smaller impact on the climate and eating a plant-based diet is the best way to reduce carbon emissions," he says.

Shiitake mushrooms are the main ingredient in Fable's mushroom product which, when cooked, aims to replicate pulled pork or braised beef. Fox says he will have the product in more than 50 restaurants around the country by the end of February.

Chiswick may not be one of them as Moran isn't rushing to faux meat. "I don't see the point of it," he says. "Just make a mushroom and beetroot burger. It'll bleed [juice] too."

How to "climate diet"

• Eat less meat, but better meat. Turn meat into a treat and make vegetables the focus of most meals.
• Eat in season. Reduce food miles by eating local food that's fresh.
• Don't waste food. Buy what you'll eat and eat what you buy.
• Eat less, generally. Most people consume too much food – there's an environmental benefit in eating as much as we need and no more.
• Ask questions. Where did this food come from, how did it get here, and do I feel OK about the supply chain and the environmental impacts?