Paris and Rome compete for food. Oxford and Cambridge compete for education. And Grass Valley and Nevada City compete to see who can toss a Cornish pasty the farthest.In this year's competition, Nevada City Mayor Sally Harris narrowly defeated Grass Valley Mayor Mark Johnson in the local tradition, held over the weekend in Grass Valley."It's all about technique and not about strength," said Harris, adding that luck played into her victory, as well.Harris will receive a trophy at Wednesday's Nevada City Council meeting for downing Johnson in the best two-out-of-three pasty toss.The city leaders tossed the unique pastry, modeled after …