Michael Gordon’s fiendishly tricky minimalist piano work from 2004 explores the entire range of the piano in ascending and descending major and minor thirds. It requires a musician of great stamina and phenomenal accuracy. All of that explains why the piece is rarely played. Step forward Vicky Chow, whose staggering performance is rhythmically tight and utterly riveting in its relentlessness. Sonatra is performed twice—first in equal temperament tuning, then in just intonation, which allows the music to float free from its rigid moorings, transforming it into a dizzying dance of colors.