FILLET of beef with rosella sauce; loin of Gippsland lamb baked in paper bark, with bunya nut puree and mint; and smoked Tasmanian salmon fillet, with lemon aspen dressing and wattle seed ice-cream. OK, so the Tasmanian salmon gives away the fact that this menu is Australian. Part of Cathay Pacific's latest in-flight menu promotion, it gives passengers on the Hongkong-Australia route a taste of ''Cuisine from the Land Down Under'' and comes in the wake of successful French and Chinese promotions. What is so unique about this style of Australian cuisine? The hitherto secret ingredient is ''bush'' food - wild fruits, berries, nuts, herbs and leaves that have been eaten by Aborigines for thousands of years. For the uninitiated rosella are scarlet petals (not the small parakeet of the same name); paper bark, bark from the mellaluca tree; bunya nuts, large, starchy nuts from the bunya pine; lemon aspen, small, sharp-tasting yellow fruit; and wattle seed, the seed from Australia's national flower which, when roasted and ground, has the flavour of coffee crossed with hazelnut. Other bush ingredients include lilli pilli, a pink berry with the texture of watermelon and a clove taste; quandong, a wild peach; warrigal greens, which resemble spinach; and muntries, small red or green berries similar to a cranberry. It is only in the past three years these exotically-named and flavoured ingredients have come into the public domain. The catalyst has been a group of innovative chefs on the hunt for an identifiably Australian cuisine. One of the leading advocates of the movement is the chef behind Cathay's promotion, Scott Webster. ''What I'm trying to do is devise a cuisine that's recognisably Australian,'' he said. ''Having worked all round the world, I knew we had some of the best quality produce available. ''Discovering bush foods has given me the key to a new taste that's uniquely Australian.'' Webster recognises that such ingredients will take time to gain public acceptance. ''It takes a while to get used to anything,'' he said. ''What I do is take our fresh primary produce and marry it with small amounts of bush food. ''I use indigenous eucalyptus and bunya leaves for barbecues, where the Americans use mesquite and hickory, and eucalyptus and macadamia nut oils where the French use olive and walnut oils. It's just a question of preparation.'' Ignorance is not the only problem Webster - and Cathay - are hoping to overcome. Because bush foods are still hand-gathered, supply is still limited. This has proven frustrating for those attempting to bring Australian cuisine on to the world stage. ''After a promotion at the Manila Hotel, one of my dishes was so popular it was kept on the fine dining menu,'' he said. ''But getting a regular supply of some of the ingredients has been a constant headache.'' Webster's style is to use these unfamiliar ingredients sparingly, not only to gain acceptability with a wider audience, but because flavours are so intense. ''These foods grow wild and therefore have a very concentrated flavour,'' he said. ''They have to be used sparingly or they can be overwhelming. ''Meat or other main ingredients should be the focal point of any dish. ''Bush foods are to my cuisine what chili is to the Thais and soy sauce to the Chinese. ''Flavourings are what enhance and add colour. They are what gives a cuisine its national identity.'' Mr Adrian Ort, Cathay's catering manager, believes it is the concentrated flavours of bush products that makes this new cuisine outstanding. ''Look how commercial production of strawberries has spoiled their sweetness,'' he said. ''Wild foods are always much more exciting.'' THE promotional menu was an educational process for all concerned. ''We first met Scott when he was doing a promotion in Kuala Lumpur,'' Mr Ort said. ''He then did a big cook-up for us in Melbourne. We tasted our way through his entire repertoire and selected those which we felt would have the widest appeal. ''Obviously we avoided the more esoteric Australian foods like emu and crocodile as we didn't want to alienate our customers. ''We also had to make adjustments when we couldn't get hold of large enough quantities.'' Webster has won many awards for his cooking. He is also consultant chef to the Australian Meat and Livestock Commission and has two restaurants showcasing his cuisine. His latest project is a recently-published book of recipes called Uniquely Australian. His first introduction to bush food came almost three years ago when he went with the national culinary team to the Luxembourg world cup competition. ''A colleague had come across a few ingredients and we used some in the competition,'' he said. ''When we returned, having won the gold medal, I chased up suppliers and began experimenting further.'' Everyone involved, including Cathay chefs, had to be trained by Webster. In novice hands, cooking with bush ingredients could be disastrous. ''Scott's cuisine demanded a complete reassessment of technique,'' Mr Ort said. Webster said: ''There were some amusing incidents along the way, including the time when one of our caterers put in an order for 500 bottles of eucalyptus oil. ''It had to be explained that because it was so strong, one bottle would last for months.'' Used to catering for the hotel and restaurant trade, Webster also had to adjust his techniques. Airline food has to survive reheating. Butter sauces, for example, which can be served a la minute in a restaurant kitchen, separate when re-heated. ''It was a double-edged knife,'' he said. ''Both parties have learned a lot during the preparation of this promotion. ''But what matters is that Cathay has a new promotion that will set it apart from other airlines, and I have the chance to bring Australian cuisine to a wider audience.'' Webster's Australian dishes will be served in addition to Cathay's normal menu, along with a range of Australian wines. A promotional video, extending the educational process from taste to sight and sound, will be shown on board to explain the cuisine and its ingredients.