Zurich - A Swiss mezzosoprano is recovering from second-degree burns after her costume caught fire on stage during a performance of Boris Godunov at Zurich's lakeside opera house, officials said yesterday. The accident occurred before an audience of more than 1,000 on Wednesday evening as Judith Schmid, playing the role of an innkeeper, was roasting sausages on a grill in a scene from the work by Mussorgsky.