From the experts:
A popular Irish name virtually unknown here — with a pronunciation that's far from obvious. It's basically SOR-ca, but with a little hiccup between the 'r' and the 'c' that's near-impossible for the English speaker to reproduce. Other phonetic pronunciations given are sir-eh-ka, sur-aka and surk-ha. Spelled Sorsha, she is a major character in the movie Willow.