Credit: Kah Poon Not “afternoon tea,” but “aftermoon tea” is the subject of a new 25-minute opera by GRAMMY-winning composer Steven Mackey and Obie Award–winning librettist Rinde Eckert. Composed in under two months, it premieres June 10 as part of Opera Theatre of Saint Louis’s “New Works, Bold Voices Lab,” which supports contemporary storytelling by American composers and librettists. Artistic {…}