Joo Yeon Sir is a rare example of a top-flight concert violinist who has also found success as a composer. She has collaborated with major composers on performances of new works. While in school, Sir formed a violin-and-piano duo with Irina Andrievsky and continues to perform frequently with her. Sir's commissioned 2018 solo violin work My Dear Bessie was based on love letters of soldier Chris Barker and Bessie Moore during the Second World War. As a performer, Sir is the dedicatee of two works by Karl Jenkins. She has released several albums on the Rubicon Classics label, including Suites & Fantasies (2017) and Solitude (2022), which contained a recording of My Dear Bessie. In addition to Andrievsky, Sir also collaborates frequently in chamber music with guitarist Laura Snowden.