In a blog a few weeks back, I reported on the winery Switchback Ridge owned by Kelly Peterson and her 2004 Switchback Ridge Petite Sirah. In this week’s blog I am reporting (one more time) on the grape variety Petite Sirah (Peh-teet-sear-ah), the American name for the French grape Durif. The grape was created in France in the 1860s by Dr. Francois Durif…