ANSWER: It's rare--especially in Germany and the Alsace region of France, where some of the world's best Rieslings are made--but it does happen.
We haven't checked out more recent vintages, but the 2005 California Riesling from Kendall-Jackson was just barely a Riesling by legal definition.
For a wine to be labeled as a varietal, at least 75 percent of the blend must consist of the listed variety. K-J's 2005 was 76 percent Riesling, 9 percent Gewurztraminer, 8 percent Viognier and 7 percent "other."
The Gewurztraminer and Viognier helped lift the blend's nose, which offered impressions of honeysuckle, pear blossom and orange blossom. And the refreshing flavor spectrum included fleshy peach, apricot and pear notes.
Did it provide a life-changing wine experience? Of course not.
But it was a refreshing, enjoyable wine... and proof that "100 percent varietal" isn't the only way to make good wine.