Having grown up in the super-smooth environs of the San Fernando Valley, the daughter of a dentist to the stars of LA, Eleni Mandell might be expected to be a shiny-toothed ex-cheerleader with a pneumatic bosom and a voice to burst bubblegum.

In fact, although she was surrounded by Valley Girls at school, she was always the odd one out. Surgery-free, she avoided the mall and spent her youth strumming her guitar and listening to Tom Waits. So when she started making music of her own, she was intent on doing it in the least plastic way possible.

“My voice is naturally low anyway, but I worked on developing my lower range, because I wanted to sound like a man,” she explains. “Not to fool people �" I just didn’t want to sound girly.”

Yet her deep vocals don’t sound blokeish or even contrived �" just rather beautifully understated, perfect for the Quasimodo jazz club in Berlin, where the lights are low and waitresses dart through the crowd. And though she may not be interested in the shinier aspects of Hollywood, the darkness of film noir certainly trickles through her oeuvre, with slow-burning numbers such as My Twin (about how the love of her life may die in an accident before they even meet) or Pauline (the other woman’s retort to Jolene) providing a sultry soundtrack Tarantino would kill for.

Yet the thirtysomething’s success remains a cult secret, despite this being her sixth album. Yes, Mandell admits, it has been frustrating remaining so underground for so long �" she recalls bursting into bitter tears after a British record label flew her to London, wined and dined her and then decided not to bother. (She admits that it was gratifying to later watch the company go bust, no doubt due to a shortage of ears in the talent-spotting team.)

She also admits that she used to complain about being compared to Norah Jones and prided herself on being uncategorisable �" until she realised that Jones sells records precisely because she is categorisable. In 2001, The New Yorker magazine called her “perhaps the best unsigned artist in the business”; Los Angeles magazine voted her the best local singer in 2004. Yet she still hasn’t, as they say in the business, shifted units. Now she is signed to V2, there is a real optimism that this may change.

It’s not all been a struggle. Being asked to perform for her all-time hero Tom Waits sweetened the journey somewhat. It happened when she was working on the door of an LA venue that belonged to her musician friend and mentor Chuck E. Weiss (the inspiration for the Ricky Lee Jones classic Chuck E’s in Loveand a man who previously ran the Viper Room, notorious as the location of River Phoenix’s death). “One day Chuck said: ‘Tom’s gonna be there tonight, I want you to bring your guitar and wear your blue dress’. So I did.

“He called me up on stage to play a song, and as I left the stage Tom Waits grabbed me and said: ‘That was beautiful’. It’s the moment I’ve been hanging on to all my life!”

Not bad work for a door girl who by day was still working as her father’s assistant in his dental surgery: “I spent six years handing my Dad sharp instruments after very little sleep.”

She’s also found a better scene in LA than the one in which she grew up. She can walk everywhere, whether it’s to the thrift stores she loves or a hike into the hills or to an early-morning ballet class. “It’s an exercise in humiliation. They say tuck your backside in, and I just look retarded. But I love it.”

And she’s close to two other local singer-songwriters, Inara George and the hotly tipped Lavender Diamond. The three of them form a harmony group called the Living Sisters, who have no ambition other than to hijack other people’s shows for the sheer physical joy of singing together.

Mandell has also cleaned up in the boyfriend department. She says that part of the reason she’s been so prolific as a songwriter is that she’s had so many bad boys to provide dark inspiration. “I felt a little overly intrigued by seedy characters. From a distance it’s what makes them attractive, but in the end it’s what drives you crazy.

“There was the commercial fisherman who wanted to be an artist, the hustler who would always be creating money out of thin air, selling his grandmother’s wedding ring and claiming it was owned by Madonna. And the rock star, and several other run-of-the-mill musicians.”

She giggles. At the start she wasn’t convinced that her current guy would be any different from the others. As she sings in her ode to him, The Make-Out King, “I can’t be seen kissing the make-out king”. The song goes on to detail his good looks and presumed Casanova ways, but redemption comes in the final line: “The make-out king is starting to care.”

Indeed, she knew it was true love when she recently caught him sneaking into her house to replace her dead pet fish with a new one.

Eleni Mandell’s album Miracle of Five is released by V2 on April 16. She plays the Troubadour, SW5 (020-7370 1434), on Tuesday