Dried octopus. Dried mackerel. Prawn eggs. The secret ingredients of XO sauce are many and they are varied. But in Australia, our chefs, many of whom have long enjoyed a steady diet of XO-enriched Cantonese food after service, are finding ever-wider applications for the sauce, just as they're pushing the envelope on what the sauce itself comprises. Today's Australian XO sauces can be vegetarian or vegan, Indigenous or Caribbean, yet they're still identifiably XO in origin. What makes them tick?
By most estimates the original hasn't been around much longer than 35 years, with most sources pointing to a handful of high-end Cantonese restaurants in Kowloon in the early 1980s as ground zero. You could be fairly certain you wouldn't find one thing in XO sauce, and that was Cognac. The "XO", which stands for "extra old" in the fancy-brandy trade, seems to have been appropriated to signify (or justify) the cost.
In essence it's a coarse, oily chilli sauce, enriched and textured by shredded dried seafood. Dried scallops are the constant in Cantonese recipes for XO and, along with dry-cured ham and dried shrimp, two of the other more common additions, they give it umami-savour and weight.
These ingredients also add significantly to the cost, with specialist dried-seafood shops in Sydney's Chinatown charging as much as $688 a kilo for their better dried scallops.
But then a little bit of XO goes a long way. And it goes with just about everything. It's good with oysters, pippies, scallops, prawns, abalone, fish, lobster, mud crab, snow crab, spanner crab and yabbies. It's also good with bitter melon, broccoli, green beans, tofu and eggs. You don't often see XO with lamb or pork, but it makes fast friends with both beef and chicken. It's also very good with wontons, noodles, rice cakes and rice.
Appreciation of XO sauce in Australia can be first pegged to the attention it received in the late 1980s at high-end Cantonese restaurants that had a close connection with Hong Kong. At Flower Drum, in Melbourne, it was something of an obsession for then-owner Gilbert Lau, who would fly to Hong Kong to source the dried seafood. At Sydney-landmark Golden Century, meanwhile, the signature dish has long been pippies stir-fried with XO sauce and served on a wodge of vermicelli. The buzz became louder when gweilo chefs joined in on the act, says Melbourne-based Asian-food expert Tony Tan. He recalls teaching an XO masterclass for Andrew McConnell and his chefs as early as 2000. "Once Andrew and Neil Perry introduced it to their menus, it really took off," says Tan. So much so, in fact, that Perry named the modern-Asian restaurant he opened in Potts Point in 2000 after the sauce. Kylie Kwong has had it on her menus at Billy Kwong since day one – most memorably, perhaps, with home-style fried eggs and tamari.
For the most part, XO sauce remained in close proximity to rice and chopsticks. But that's no longer the case. While the condiment is used inventively at the likes of Melbourne's Sunda (with egg noodles, chicken crackling, and pepperberry) and Spice Temple (stir-fried with morning glory), it's also finding its place outside the context of Asian restaurants. At Saint Peter in Sydney and Three Blue Ducks in Brisbane, it's deployed along broadly familiar Chinese lines, with a coral trout head and as an XO butter with Moreton Bay bugs, respectively. But at The Press Club, Melbourne's premier contemporary Greek fine-diner, chef Reuben Davis goes further, slipping XO sauce into a horiatiki of Clarence River prawns, melon and mint. At Bistro Blackwood in Adelaide, XO joins the dots between Brussels sprouts and bunya nuts, and at Bentley, Brent Savage teams it with squab. The menu at Momofuku Seiobo, meanwhile, features a "Caribbean XO", which combines habanero chillies, shallots, garlic and ginger with salt cod, abalone and annatto.
Seiobo's Barbados-born chef Paul Carmichael created his own version of XO earlier this year to accompany a take on ducana, a Caribbean sweet-potato dumpling. "I love XO's depth and versatility," he says, and has since used it to sauce brisket, with cou cou, and in the restaurant's staff meals. "I even made a pizza with it."
For Jock Zonfrillo, chef of Orana and Bistro Blackwood, the flavour of XO sauce is special, not simply because it's intense, but because it's layered. "The scallops, the shrimp, the ham, the fermentation, the chilli and the prawn roe are interesting in a dried form, but when you cook them down together to a paste and let it out with a solid aged chilli oil, you're left with a sauce that changes on the palate from start to finish at least five times," he says. "When you add that to a fresh ingredient, be it vegetable or protein, both the sauce and ingredient benefit from each other's company." For one of his house XO variations, which is vegan, Zonfrillo works to mimic those layers by drawing on Orana's bank of fresh and fermented Indigenous ingredients. "It's intense, and not vegan-tasting at all thanks to the depth and complexity," he says. "And because of the cost of the native stuff, it's in keeping with the tradition of it being super fucking expensive."
But can you really make a vegetarian or vegan version of a sauce that is essentially defined by the presence of dried shellfish? There's vegetarian XO with silken tofu, pickled long beans and mushroom floss at Queen Chow in Sydney, while a vegan XO dresses steamed tofu with white soy and roasted-chilli oil at Lee Ho Fook in Melbourne. "XO sauce is an oily dried scallop and prawn condiment," reasons Victor Liong, chef at Lee Ho Fook. "So the vegan version usually tries to mimic the flossy texture of the dried scallops." Liong achieves this with shio kombu, sun-dried tomatoes and dried shiitakes, upping the umami with mushroom-soy and other soy-based condiments.
For Paul Carmichael at Seiobo, XO sauce has a strong association with Australia. "I wanted a dish to connect the Caribbean to Sydney. I'd heard of XO before I came here, but it was being here that really inspired this version," he says. "The next step is to get it into West Indian homes."