The unusual, apparently, is in fashion. At least when it comes to classical music. In the past few years, we have seen the classical charts topped by Bach's Goldberg Variations played on a harp; a flamboyant young American organist given to playing the keys with his feet; and, in Milos Karadglic, the long-awaited return of the star classical guitarist. In which context, the signing to the ultra-prestigious DG record label of Avi Avital, a 33-year-old Israeli mandolin player, is perhaps not so surprising. What he does with the instrument is very likely to be.

I first came across Avital at the Eilat Music Festival last April, where he had a restless group of teenagers riveted despite the fact that he was recreating the music of a Venetian Masque on, well, a mandolin.

It was the combination of wonderfully sensitive yet nimble playing with a charismatic stage presence (it certainly does not hurt that he plays the mandolin with the same kind of loving fervour with which a rock guitarist might cradle his guitar).

So if the major label thinks his forthcoming album of Bach transcriptions could sell in decent numbers, they may well be right.

But to the musician himself, nothing was calculated - not even the decision to learn mandolin. "God put a mandolin into my hands. Who says he doesn't have a sense of humour," he smiles over coffee at Café Rouge at Heathrow en route to Berlin.

He plays mandolin with the fervour of a rock guitarist

His biblical reference is apt as the love for this uncommon instrument came, if not from God, then at least from above. "I was a little boy living in Beersheba and my neighbour upstairs played the mandolin. So I wanted to learn."

This is not quite as random as it sounds. It was Avital's first teacher, he explains, the Russian violinist Simcha Nathanson, who created a hub for mandolin playing in the desert city. "He arrived in Israel in the '70s and asked the local conservatory if he could teach violin. They told him they already had a violin professor, but that they had 20 mandolins in the basement and, if he wanted, he could teach mandolin." Nathanson did just that, starting a mandolin orchestra that flourished and, by the time Avital joined, was 40-players strong with two recordings to its name.

Yet if Avital is unusual among mandolinists, this too is because of Nathanson. "He was a violinist," he explains. "Everything he taught us, even how to hold the mandolin, was from that viewpoint. Until I graduated, I was playing mostly violin repertoire because that's what he knew." But this gave the young player a unique insight. "Sometimes I almost forget I'm holding a mandolin. He taught me music. The instrument to me is not the point."

Still, he realised that if he was to reinvent the mandolin, he would have to learn its orthodoxy. So, after a military service that saw him enlisted as a mandolin player alternating office work (his colleagues were the now-hugely-successful Jerusalem Quartet) with concerts for soldiers, he headed to Italy, the home of the mandolin.

"I was still only playing violin music, even though I was winning competitions with it, so I went to meet this fantastic Italian teacher, Hugo Orlandi, in Padova." Orlandi, one imagines, had seen a good many mandolins in his time but even he was taken aback to see the highly unusual Israeli-made instrument the young hopeful arrived with (Nathanson's influence had been so far-reaching in Israel that manufacturers actually made instruments to suit the needs of violin music - more sustained sound, louder, warmer, very different from the Italian tradition). No sooner had Avital started to play the Mendelssohn violin concerto, than Orlandi begged him to stop and swapped the Israeli instrument for one of his own. "This," he said, "is the mandolin." And, recalls Avital, the bright, stronger attack, the faster decay of the sound, was a revelation.

"For a year, I was just playing scales to adapt to the Italian traditions until I knew the mandolin's roots. But I knew I was never going to become a traditional player."

Isn't that the new tradition, I wonder? After all, the mandolin has been adopted by bluegrass, jazz and so many other musical niches, does it even have a rigid identity anymore? He thinks tradition is important. "The plucked string instruments were always the main instrument in so many cultures. Even today, the world's most popular instrument is guitar; in China they have the pipa, the bazooka in Greece, the balalaika in Russia and so on. It always goes back to that ancient kind of sound."

Ancient? Jewish culture has a great deal of ritual that acts as a line through history, through tradition and its reinvention. Does the mandolin, I ask, play that role for him? "I do connect," he answers thoughtfully, "though it's not the mandolin necessarily, which is just an instrument. But the Hebrew word omanut, meaning art, has the same root as the words imun, to practise, and emunah, which is belief or fate. This connection of believing in something and practising, the doing of it, combined in the two words put together - omanut, art - this has a great resonance. In this sense, playing music is almost a religion for me."

As for the music of today, what really excites him, he says, is the synthesis of different kinds of music. When the Israeli composer Avner Dorman wrote his mandolin concerto for Avital (the recording of which was Grammy-nominated), Dorman channelled bluegrass, Middle Eastern traditions, Brazilian music. "New music brings together so many elements, and every time I play that concerto it's a trip," grins Avital.

His cross-genre explorations brought him to the door of the man whom, one senses, is the most important musical figure in Avital's life, the great klezmer clarinettist Giora Feidman. "He's like my adopted grandfather," he enthuses. A grandfather you go on tour with and bring audiences dancing to their feet.

"It was Giora who made me understand that concerts are more than entertainment, that they need spiritual food. And as an artist you are a vessel to serve this purpose."

If these do not sound like the words of a showman, DG's executives need not fear. Feidman has taught his protégé some tricks of stagecraft along the way. "I learned from the way he goes to a concert hall and understands the energy of the audience in a second," says Avital, "He holds it and he plays with it. It's like magic." There's admiration in his voice, and an unspoken promise not to let that privileged tutelage go to waste.