What does a bass clarinet look and sound like? Even classical aficionados can be hard-pressed to answer that question. Hardly any concertos have been written for the instrument, buried deep in the underbelly of the orchestra.

One exception is "Prometheus" by American composer Geoffrey Gordon. First heard earlier this year in London, the work received its U.S. premiere Thursday morning at Orchestra Hall.

The soloist was Timothy Zavadil, Minnesota Orchestra's bass clarinetist. Stationed at a music stand, with his instrument perched on a spike (its saxophone-like bell jutting toward the audience), Zavadil gave a commanding performance.

Gordon's piece is based on a prose fragment by Franz Kafka, outlining four strands of the Prometheus story in classical mythology. In the first two, Zeus clamps Prometheus to a rock — his liver pecked at by circling eagles — as punishment for giving fire to humans.

Gordon found striking counterparts for these events in his fulminating, expressive orchestral writing. Spitting trumpets suggested the sharpened talons of raptors. Deep percussion rumbled with the dark psychology of predation and physical chastisement.

Zavadil's ripely rounded bass clarinet tone bestowed an element of dignity on the suffering Prometheus, tracking his gradual obliteration from public memory through a twisting solo cadenza to the unsettling memory-wipe of the piece's fade-to-black conclusion.

Unusually, the program features a second contemporary concerto after intermission. Icelandic composer Haukur Tómasson's Piano Concerto No. 2 was premiered two years ago by fellow Icelander Víkingur Ólafsson, who was again the soloist on Thursday.

Tómasson's concerto was in some ways the sonic obverse of Gordon's — the piece sounded bright and glittering where "Prometheus" was murkily subterranean.

It's easy to see why Ólafsson won the BBC Music Magazine's prestigious Recording of the Year award for a recent release of Bach's keyboard music. His mercurial temperament and crystalline technique were prominent in Tómasson's concerto, which focused more on shifting rhythms, pulses and textures than on traditional harmonic and melodic juxtapositions. Ólafsson's solos glinted like dripping icicles from the piano, interacting delicately with small groups in the orchestra and the sinuous violin of concertmaster Susie Park.

Music Director Osmo Vänskä is a superb accompanist in concertos, and drew strongly characterful performances of unfamiliar music from the players.

The two concertos were flanked with works by Beethoven and Sibelius, two longstanding Vänskä specialties. A slightly hard-driven account of Beethoven's Prometheus Overture opened the concert, but the real treat was the sizzling account of Sibelius' great tone poem "Tapiola" (which closed the concert).

Vänskä is a master of this music, and his interpretation combined an appreciation for the complex motivic structure of "Tapiola" with a fieriness that never seemed impetuous. The scintillating intensity of the polyphonic string chorale and the cellos' eloquent interjections were two obvious highlights. But really, the entire performance was gripping from start to finish.

Terry Blain is a freelance classical music critic for the Star Tribune. Reach him at artsblain@gmail.com.