The Old Woman and the Imp

In a variation on the tale of Rumpelstiltskin, an old woman lands a job as a cook in the local inn. Unfortunately, while she is an expert spinner, she doesn't know the first thing about cooking. With the help of an imp who offers his services, she will appear to be a master cook for one year, but at the end of the year she must offer up at least one riddle that the imp can't answer, lest she become his slave forever.