Why is it that this brooding black grape hasn’t had its day in the American sun like so many others? Chardonnay had its day. Merlot had its. Pinot Noir is still taking bows, even more than three years after that movie. Zinfandel has been the bad boy rock star for years, drawing more than 10,000 groupies to San Francisco every year to celebrate its brawniness. Even Riesling is on the rise. Sangiovese had about a minute in the spotlight and Syrah seems to be sputtering along. And, of course, there’s Cabernet Sauvignon, which has always been the leading man.