That would be "Verklärte Nacht". I have three different recordings, one by Herbert von Karajan and the Berlin Philharmonic Orchestra on DG and two chamber versions which I like better, one by the Orpheus Chamber Orchestra on DG and the other by the Hollywood String Quartet with Alvin Dinkin and Kurt Reher on Testament.
I'm not into Schoenberg's vocal works and I don't have much of his other work, just Rafael Kubelik with the Chicago Symphony Orchestra in the 5 Pieces for Orchestra, Op.16 on Mercury and the solo piano recordings by Maurizio Pollini in his earlier years on DG. Maybe I should try the string quartets (Leipzig Quartett?) and violin concerto (Hahn?) again.