It's annoying that contemporary music, as far as your audition piece is concerned, is music composed by someone who died after 1950. This eliminates virtually all the impressionist composers, Webern, Berg, and even Bartok...
Anyway for a non Prokofiev lyrical piece, I recommend:
-Shostakovich Prelude and Fugue No. 4
-Liebermann Nocturnes and Etudes
-Sibelius Impromptus (no. 5 is my favorite) and Romances
The problem with Sibelius, is that he probably won't be considered a contemporary composer even though he fits your definition. For bigger contemporary works take a look at Corigliano's Etude Fantasy and Carl Vine Sonatas.
Try to get past your distaste for Prokofiev! Try Prok's 3rd Sonata - it has a gorgeous lyrical section in the middle.