Trends: Charcoal is the new black

Believe it or not, fast-food chains can be barometers for what's hot. Take charcoal. An ingredient that's been quietly burbling away, used in Asian cooking for eons, suddenly gushes onto the mainstream with Burger King in Japan unveiling its black 'Kuro Pearl' burger.

The Kuro Pearl is a cheeseburger featuring a slice of black cheese between a couple of jet black buns. The outlet's other new offering, the 'Kuro Diamond', adds tomato, lettuce and onion to the mix if you're in a more colourful mood.

The bun's striking black colour is due to the use of 'bamboo charcoal', while the patty's slathered in a sauce that uses the more recognisable dark touch of squid ink.

While the Kuro Pearl is sparking double-takes and online confusion ("No, it's not burnt," offers The Guardian), it isn't the first time a black burger has made restaurant menus. Japan's Burger King first gave it a run back in 2012, while European chain Quick tried it with their Star Wars-themed Dark Vador burger that same year.

In Australia, it's rigdy-didge to cook on charcoal, but to eat it, well, we're coming around.

"Last year people thought our black pastry cases were little bowls, and would scoop out the fillings with a spoon rather than eat the black pastry," says Sarin Rojanametin from Nora bakery. "This year, it's not such a new eating experience." Nora (opening in Carlton, 24 September) supplies cafes-about-town with individual tarts, like coconut pandan, fried shallot crumb, toasted wild puffed rice and coconut flakes. The pastry bases contain activated coconut charcoal. "Jean [Sarin's partner] and I are Thai, the use of charcoal in desserts and in medicine is common there," says Sarin. "The activated charcoal removes toxins, and imparts the black colour."

South Yarra cafe LuxBite has been making its Bamboo Oolong Tea macaron, made using bamboo charcoal, for a few years. "We took the 'charcoal' out of the name, so we didn't scare people too much," says chef Bernard Chu. "It sold better after that. Bamboo charcoal doesn't affect the flavour or texture of a dish, and is a completely natural colour that's safe for pregnant women and children."

Before even the burger giants released their black burgers, we had our own version in East Brunswick garnering a following. Sam Hopkinson, chef at Temple Brewing Company, created the Midnight Burger, made with jet-black buns, a beef patty, house-cured bacon, gruyere, relish and pickles, to match a black IPA beer they brewed back in 2013. The beer moved on, but the burger stayed. "People come for the burger, we can't take it off," says Hopkinson. "Initially, we tried using squid ink to colour the buns, but it stained everything and was too messy." He says. "Charcoal gives a consistent colour without having to work the dough too much."

Sydney has its own Black Widow burger, made with vegetable charcoal, which chef Sean Connolly debuted at The Morrison last year. "It's kind of hard to take it off the menu, really," says Connolly. "If we sell 100 regular burgers, we'll sell 50 black burgers on the same day. I'm still surprised by how many people still want to eat it."

Back in South Melbourne, innovative cafe Kettle Black has a crayfish roll, the bun sprinkled with ash. "It's a sentimental thing, really," says chef Jesse McTavish. "It reminded me of charcoal-blackened crayfish cooked on an open flame on a King Island beach." Mctavish uses the same activated charcoal to stain the cafe's salt flakes.

For health reasons, sentiment for home or holidays, or just for a sensational look, charcoal is the new black.