Koji has been used by Japanese cooks for centuries to make everything from soy sauce and sake to miso and mirin. It's a living food made from steamed rice treated with a mould called Aspergillus oryzae, and if you love umami it's about to become your favourite seasoning. In Sydney, at Momofuku Seiobo, koji butter brings out the sweet brininess of marron.
At Yellow it amps up snake beans and black rice. Tomoko Onuki, co-founder of Rice Culture, has been making organic dry koji and miso by hand in Nerang on Queensland's Gold Coast since 2012, supplying locals such as Halcyon House's Paper Daisy restaurant in Cabarita. This year Onuki and partner Yukiyo Copley began production of shio koji, a fermented sauce of koji, rice, salt and water that not only seasons but also draws out natural flavours and tenderises meat. "It has 30 per cent salt to koji, but it's so much healthier [than salt], and you use less because of the umami," says Onuki.