Lou Harrison's setting of an Esperanto translation of the Heart Sutra for large chorus, his American Gamelan, harp and organ. Harrison's incorporation of some features of Indonesian music, modified to accord to his theories about just intonation, is quite successful in his own terms. It isn't Indonesian music, as such and it's certainly not tonally or harmonically challenging in ways that the music of Charles Ives' or Carl Ruggles' music is. Both of whose music Harrison promoted as it was widely ignored. Neither is it the brain dead neo-tonalism that became popular in recent decades.
For more about La Koro Sutro, here are notes from The Providence Singers with an English version of the text.
Another piece of Harrison's Music I like is his Suite for Cello and Harp. It's an early exploration of what could be done with the most radically limited of tonal material, a different kind of minimalism than that of Glass and Terry Riley. Except in the fourth movement which, if I recall correctly, is a setting of a movement of his Symphony on G. The music critic Richard Dyer once remarked that Harrison had something of a sweet tooth, musically speaking, but his music isn't cloying and is not overly so.
Update: Yep, it's part of the fourth movement of the Symphony on G, or maybe it's repurposed the other way round. And here's a clearer recording of the Suite.