Nothing sounds so good as a roast being placed directly on hot rocks. There's an immediate sizzle and spit — and then there's the aroma This is cooking an umu and it's one of the small traditions that many of the growing Samoan diaspora in Australia carry out to keep a link to their culture. According to the last census data, Samoans are the largest single group claiming Pacific Island ancestry, and with a population of about 75,000, more than triple the number of those claiming Papua New Guinea