Born in 1976, he actually hails from Samoa, and the first thing I learn when he begins to talk - with a gentle Kiwi twang - is that we mispronounce that country's name: the accent is on the opening syllable. Moreover, his own first name is Fa'afetai, meaning "thank you". "My middle name is Jonathan," he adds, "which is Hebrew for 'a gift from God'. I was given those names because I was born with a hole in my heart, and it closed up naturally. But Jonathan was an easier name to use at school: it meant I didn't get teased and, therefore, didn't have to beat anybody up."
Singing has always been a part of his life. His factory-foreman father, who had big sideburns and sang with a rock band, was known as "the Pacific Island Elvis". Young Jonathan chose to sing in choirs - at school, in community centres and, above all, in church. Samoan culture, he says, is strongly religious. "And it's also about respect for tradition, for your extended family, based on the teachings of the Bible," he says. "I loved singing Bach, but I also loved running riot with my friends." What sort of voice did he have at that time? "Nothing much - it was woolly - but it had potential. I was distraught when it broke early, as I had aspirations to sing big soprano solos."
But only in choirs, and only for pleasure. "I didn't think of it as a job, because where I'm from, nobody did," he says. "You couldn't make a living as a singer in New Zealand." He decided to study law. "I was fascinated by it," he says. "I was argumentative, and I was told I was good at it - I could make the most wrong things sound right, which is what a lawyer's job is. Getting that law degree was - still is - the highlight of my life, because it didn't come easy to me. I worked my proverbial off, to get good marks." Not even winning New Zealand's most prestigious singing contest could dissuade him from staying to finish his studies, despite blandishments to come and seek his fortune in London.
Eight years on, he's well on his way to finding that. He was taken on as a Vilar trainee at the Royal Opera House, and critics were soon extolling his bass-baritone voice in culinary terms: "sumptuously honeyed", "richly creamy", "like slow-melted chocolate". And when his rounded form appeared as a half-naked Papageno at Glyndebourne, they went into gourmet ecstasies. Even clad in a sober suit at the Wigmore Hall, he casts a golden glow. Earlier this year, he made his debut at the New York Met.
But the recital room is where he feels most at home. "That's where you're most exposed," he says. "Just you and a piano. For some reason, I get a kick out of the danger. When you're in a large house with a big orchestra and a padlock on your mouth - as I am when I sing Papageno - it's hard for people to tell if you're singing well. On stage, I like to live as dangerously as I can. I don't want my performance to sound manufactured. I want it to seem like the thoughts are just coming into my mind."
He's been described as the next Bryn Terfel, a label which doesn't dismay him at all, because that man is his favourite singer. Lemalu has never shared the stage with Terfel - never even met him - partly because there's usually need for only one voice like theirs at a time. "But I'd like to just hang out with him," he says. "He's got the vocal prowess I hope to achieve, and he's charismatic, down to earth, focused. There's a big heart, and a humility that shows through in his music. And his voice is seamless from top to bottom. That's what good voices are."
When I suggest that Lemalu would make a superb Sarastro in The Magic Flute, he goes into a complex disquisition on the changing nature of his voice. "The weird thing is that when I first got here, as a baby bass, I could still sing that part, but now my sonority and colour puts me too high for it," he says. "A bass-baritone is neither a bass nor a baritone. I'm lucky in that I can do Figaro and Leporello, and probably sing the notes for Giovanni, but it's not just the vocal thing; it's the character of your sound.
"And right now, at my age, with my character, Leporello is my role. Masetto I'm happy to do, Figaro is fine, and Basilio - that's the advantage of sitting in the middle. My job right now is to continue to push the boundaries of my voice, both up and down. I want to retain the richness and the dark texture, but I want to take them right up to baritone, to Bryn's level."
But of his dream roles, "it's hard to say". "I'm in a Mozart-Handel place now - Papageno, Figaro, Leporello, Masetto, Guglielmo - the servant role, the common role, the naïve ambitious role - but that's the way I am. The young singer, hard-working and ambitious. Papageno is probably the most ignorant guy on stage, but he's kind of the people's character. That's where I am right now. Why rush off and play grown-ups? Why not enjoy the fact that you're young and do young roles. When I hear 25-year-olds whining because no one wants them for King Philip - why? There are 35-year-olds who can no longer play Papageno, so do it while you can."
But what most impresses in recital is his linguistic prowess, a tribute to the long hours he's put in to master French and German, the latter being the language he considers healthiest for his voice. "I enjoy it the most," he says. "It speaks most to me, and with the things I sing in it - Schubert, Brahms, Wolff - the relationship between words and music is so clear. The first solo song I sang was 'The Erlking', and that marked me for life."
The CD he's working on will consist of English and American songs by Samuel Barber, John Ireland, Benjamin Britten, Roger Quilter and Gerald Finzi, and when I mention my lack of love for the last pair, he puts me firmly in my place. "Come on, they're up there with Schubert," he says. "It's not the cheesy Vaughan Williams thing; it's quite intellectual."
Lemalu feels 100 per cent Kiwi - and the same for Samoan. He often sings Samoan encores at his recitals, but is irritated when people want him to sing them with piano accompaniment. "It's not that kind of music - it's choral and a cappella." He'd ideally like to do a CD of it - ballads and hymns, with organ or guitar, and his father would be "language coach". Why so? "You always need a language coach, even in English," he says.
Lemalu has just been touring Croatia with his fiancée, the mezzo-soprano Sandra Martinovic, meeting her family and scouting Dubrovnik for a church in which to marry her next year. What are his more distant dreams? "It sounds a little clichéd," he says, "but I think I'm living my dream now. The career is pursuing its path, and I'm enjoying the ride."
'Des Knaben Wunderhorn', Prom 46, Royal Albert Hall, London SW7 (020-7589 8212; www.bbc.co.uk/proms) Thursday, 7.30pmReuse content