Taking as long as it takes

First the tea-making ritual. A little something carried over from her Japanese heritage. Darjeeling First Flush (the chosen blend) is meticulously measured into an empty muslin teabag, the filtered water boiled but gently cooled between jug and teapot. Then the infusion. Four minutes, precisely. After three minutes, "it's too much of a wake-up tea"; after five, "already too bitter". So, four minutes. Choose cup (size first, then colour), remove teabag, dispose. Serve. Enjoy.

And as with tea, so with music. Preparing it, sharing it, takes time. Patience. This is Mitsuko Uchida. Precise, uncompromising, passionate. The tea-making ritual - with its studied but enthusiastic commentary - will have been repeated many times for other visitors, but each time will be the first time. The flavour of the tea depends upon it. Knowing just how much care has been lavished on its preparation only adds to the enjoyment. Uchida knows that. She can make an occasion of the simplest task. She has presence. A quality. And that quality is mirrored in her piano playing.

So, how to define it? Words won't really suffice, though we can try a few: supple, rapt, searching, dream-like. But volatile, too. You see it in her manner, you catch it in her conversation. One moment she will be quiet, confidential, almost conspiratorial - as if sharing the secrets of the universe with you alone. The words will be carefully considered, sparingly used, a series of portentous haikus separated by equally portentous silences. But then something will be said, something implied, to excite her, provoke her, and the new idea will detonate with such force that every word is suddenly an exclamation. So she thinks and speaks rather as she plays - a familiar trait among musicians but more pronounced in her case - and she plays in such a way as to persuade you that every phrase is precisely as you would choose to play it were you to do so. That's rare.

Uchida has just emerged from a period of "hibernation". No public performances, only private ones. This is a biannual occurrence. For two two-month periods every year she accepts no engagements. It's true that every second summer she'll take off to the Marlboro Festival in Vermont, there to make chamber music "just for the sheer hell of it", but working vacations are generally spent tucked up in her little mews house off the Portobello Road, taking stock, recharging the batteries, learning new repertoire. Her shortlist of priorities currently reads: the Brahms and Bartok Second Concertos, the Chopin Preludes, the Beethoven Diabelli and the Bach Goldberg Variations and the 48 Preludes and Fugues (to be ready in time for her 70th birthday in the year 2018), and the Ligeti Concerto. While "slaving" over the Birtwistle Concerto a couple of years back she decided that she would learn at least one major contemporary piece every three years. Maybe open a few ears.

She loves these sabbaticals "at home". They are so much a part of what she is about: a balanced, orderly existence with time to think, time to dream. And London is home. As witness her unshakeable allegiance to "Marks & Sparks" (the English colloquialisms slip deliciously, eccentrically, into her conversation). She begrudges time spent travelling. A typical day in the life of Mitsuko Uchida begins slowly. She gets up "s-l-o-w- l-y" (her intonation tells you just how slowly). A first cup of tea (prepared, of course, as above), then back and forth to bed with mail or newspapers. Then brunch - "only a bite, because otherwise your energies go into digestion" (before a concert she'll enjoy a single Bendick bittermint) - a quick glance at "Modesty Blaise" in the Evening Standard, a hand or two of bridge (don't look for reason in the apparent incongruities here), and off across the courtyard on the short walk to her studio where two Steinway concert grands - her own - await.

Right now she's preparing for her Barbican Celebrity Recital on Wednesday. A typical Uchida programme, it opens, like the proverbial floodgates, with the Berg Sonata, continues with Schumann - his Davidsbundlertanze - "two true romantics", she says, "the only thing separating them is about 100 years" - and concludes with Beethoven's last sonata, Op 111, its pearly trills stretching all the way to infinity. She's played that piece often, though intermittently, over the past 20 or so years and each time she does, another problem gets solved. She won't enlarge upon what it is this time - not while the work is still in progress - but she's happy to explain the process: "I just play, and if it doesn't sound right, I play again, or I dream and play, just let it happen, until me, the listener - not me, the player - thinks, `Ah, that was it!' And then me, the player, reconstructs exactly why it was right. Sometimes this process takes months, years. And then you want to find out why it took so long to settle, why you could not do it then but can now!"

It's this delicate balance between emotion and intellect, instinct and reason, intuition and calculation that gives Uchida's work its edge. She describes in painstaking detail how she believes she's finally found the solution to a single bar of Beethoven's Emperor Concerto. It's the moment where the second subject modulates from B minor to B major and it all happens in one tiny phrase. She used to feel that phrase as a crescendo, until she realised that in order to stay, as Beethoven requests, pianissimo, then you must imply, if anything, a diminuendo. "B major suddenly opens up. It's a different glow," she says, with the effusiveness of one who's just happened upon the lost chord. But it's almost as thrilling to hear her talk about it as play it. Almost. "Thank God," she says. "Otherwise we'd always be talking, not playing."

Either way, she's a natural communicator. With her audience, with the composers she plays. Not a week goes by that she doesn't commune with "her composers": Bach, Mozart, Schubert, Beethoven. She is tirelessly inquisitive on their behalf. She will repeat the same phrase over and over, for as long as it takes to reveal itself. The process never bores her, provided the music doesn't (and she has her mental blocks - Rachmaninov is one). Even as a child she was happy to explore her favourite stories again and again, hoping against hope that she might discover something new.

Childhood was a tale of two cultures. Her father was a Japanese diplomat. Which meant that there was life beyond the clouds, beyond Japan. The family landed in Vienna when Mitsuko was 12. A lucky escape, she now believes. She found her "first love" there. Franz Schubert. This month sees the release of her first Schubert album - the Impromptus Op 90 and Op 142. It's taken a while, or rather it's taken as long as it's taken, to get this music "into her way". And to find the right piano for it. The piano in question resides in Uchida's studio, and it goes by the name of "Chaliapin".

Inside the studio, Uchida feels her way through the opening page of Schubert's last sonata, music caught "somewhere between love and sorrow" (Schubert's words). The trill in the left hand rolls out like distant thunder. The sound of the instrument is indeed rich and welcoming, warm and subtle like the great Russian bass whose name "he" shares. "Chaliapin" has, says Uchida, settled down nicely since his new hammer-heads were installed. Her piano technician has developed the sound according to his character (very important - "you cannot impose character upon an instrument - each one is different"). He sounded particularly well in the Musikverein, Vienna (Uchida's favourite concert hall), where the Schubert recording took place. Almost too warm, in fact: "There is usually some element of frost in Schubert," says Uchida with a theatrical chill in the voice. "Chaliapin" stands back to back with another Steinway, also male (all Uchida's pianos are male). He is super-cool, immensely transparent, ideal for Debussy: "I mix colour and he makes it very clear - quite the reverse of the other one." A third piano resides in the house - "for emergencies".

A while back, Uchida devised a series of concerts built around the music of Schubert and Schoenberg. Her aim was as ever to open people's ears, to encourage them to listen differently, to hear beyond consonance and dissonance and maybe, in doing so, to discover, contrary to first impressions, that the real conservative is Schoenberg, that the craziness actually lies within Schubert. "By saying `I understand Schubert but not Schoenberg', I believe people are misunderstanding the word `understand'. What they are really saying is - `That sounds pleasant to me because I got used to it, but that is just a noise because I refuse to hear it' ... People remember what they can easily grasp, and what they can easily grasp, they like to repeat. We live in such an impatient age, an age of soundbite psychology and compilation albums - both of which I hate! Nothing in music is short!"

But the statement is. Short and frank. What do they make of such statements in Japan? How do they now view Mitsuko Uchida? "Like a strange, exotic bird! I imagine they look at me and think - she sort of looks Japanese, she speaks Japanese, but... Look, I still speak the language well, but whatever language I use, I want to be as clear as possible. In Japan, you never say exactly what you mean. Politeness is all. Politeness is more important than honesty. And that I cannot accept." Of course not. Great musicians never lie. At least, not in front of an audience.

Uchida plays Berg, Schumann and Beethoven: 7.30pm Wed, Barbican Hall, London EC2 (0171-638 8891)