Unsuk Chin Day, Barbican

A great shame because what was revealed over the course of two concerts and a film of her only opera was a seriously impressive composer. Many of her skills could be glimpsed in the first work of the day, Gougalōn, which was being given its UK premiere by the London Sinfonietta and conductor Stefan Asbury. Chief among her abilities is with colour. We who know our postwar composition might imagine that we've seen it all when it comes to experiments in timbre. Not so. Gougalōn throws up such a dense forest of percussion that the two Sinfonietta percussionists seemed only just able to get on top of it all by sprinting Usain Bolt-like from one to another.

Gougalōn's second movement, titled Lament of the Bald Singer, sees the entry of a ghostly waltz - a little reminiscent of Adès's Powder Her Face - inhabited by some beautifully calibrated elements, including a family of brushed sounds and glissandos (a recurrent theme). There's some blazing virtuosity in the canny metalophonic portrait of The Grinning Fortune-Teller with the False Teeth, and some intriguing dissonant string writing for the final Dance Around the Shacks. Here were pictures of the Orient that refused ever to be orientalist. New sounds were being constructed through new stories: those of the Korean street.

Perhaps inevitably, the further back we went into her oeuvre, the more shaky she seemed in unfolding long spans of music. Yet even just out of university, her voice was distinct. The earliest compositions we heard, Acrostic Wordplay (1991, revised 1993), sung with great panache by Yeree Suh, reveals seven discrete emotional states, many of them attractive, some, such as in The Rules of the Game which was delivered in a girl's voice, disconcerting.

Her music from the 2000s, packed full of post-minimal games, enters a new phase. The choral work, Kālá (2000) - helped by an impressive last-minute bass replacement from the BBC Singers, Adrian Peacock - rises from the depths and calls on Daphnis and Chloe and John Adams on its journey to a chromatic apotheosis. Her Violin Concerto, which won her a Grawemeyer Award in 2004, gets down to a TGV-like chase with the BBC Symphony Orchestra under the ever-curious Ilan Volkov, after a heavenly initial open-stringed breeze. It is iterative and virtuosic, rarely pausing for breath, violinist Jennifer Koh delivering all the furious double-stopping with bow-destroying aplomb. But, with little melody and a lot of inaudible mid-register weltering, I wasn't sure this particular sweaty chase was worth it.

More memorable from this period is her Double Concerto (2002) for percussion and piano. Percussionist - the sparky little Oliver Gunnell - again has to dance around his enormous instrumental spread in conjuring up an opening metallic shower and an extraordinary jungly dance with the double basses. Dense ostinati writing weigh the work down around the middle. But by now Chin had built a bridge to her most recent compositional phase. A more organic evolution to the composition could be heard. And, throughout, there was the beguiling encrustation of the crystalline fuzz of a prepared piano to admire.

Chin is no slouch either when it comes to vocal writing. The film of her only opera Alice in Wonderland, which was premiered to great fanfare at the Bayerische Staatsoper in 2007, showed her skill in being able to carve out melismatic melodies and build a lithe, lyrical drama from the orchestra. Some of the music seemed to rub up against the episodic and intellectual exercise that is Alice's absurdist journey. Indeed, all Chin's vocal work seems to suffer slightly from her penchant (no doubt picked up from her many years in Germany) for nonsense verse.

We ended with an oddity: a concerto for the Chinese mouth organ, the Šu. The performer, Wu Wei, balancing what looked like a model church organ on his lips, bobbed around, desperately trying to make some headway with his soft trembly electronic sound against a large orchestra. It didn't work for me. But the penultimate piece Rocanā (2008) very much did. Packed with several changes of pace and scene, her trademark glissandi and ostinati tempered and complicated by polyphony and percussion, Rocanā is perhaps her most rich and rewarding piece to date.