The piece
Chopin dedicated both Op. 55 nocturnes to his Scottish pupil Jane Stirling. This one starts from a very bare theme: an F minor melody, Andante, over a bass and chords on every beat, which comes back several times, almost unadorned. A central più mosso section breaks this calm with triplets played an octave apart by both hands and forte chords; the theme returns briefly, then a coda in triplets, molto legato e stretto, closes on rolled F major chords.
Technique is not the main hurdle here: with such a plain theme, everything lies in the sound and the phrasing. Let the melody sing and keep the accompaniment one notch below it. In the central section, the two hands an octave apart must sound as a single line, perfectly together. The rolled chords at the end unfold slowly, from bottom to top, with the pedal holding everything. In the coda, the triplets stay connected despite the stretto: check at a reduced tempo that every note of the triplet is even, then press forward little by little.