Chilean Sauvignon Blanc may not sound especially unusual, but the story of this wine is surprising indeed. For many years, it turns out, Chilean Sauvignon Blanc wasn’t Sauvignon Blanc at all.

According to The World Atlas of Wine, much of what was sold as Sauvignon Blanc “was actually Sauvignon Vert or Sauvignonasse” (The Oxford Companion to Wine considers these two varieties to be synonymous). Despite their names, they have little in common with Sauvignon Blanc. The Oxford Companion notes that “wines produced from Sauvignonasse are much less crisp and aromatic than those of Sauvignon Blanc.” The Sotheby’s Wine Encyclopedia has less patience with Sauvignonasse, simply stating that it’s “not related to Sauvignon and has no Sauvignon character whatever.”

Tom Stevenson, the author of The Sotheby’s Wine Encyclopedia, was frustrated by Chile’s unwillingness to distinguish between Sauvignon and Sauvignonasse, and he made a trip to the vineyards himself. In addition to plenty of Sauvignonasse, he discovered acres of confusing mutations and crosses: “Sémillon with Sauvignon, Sauvignonasse with Sauvignon, and Sauvignonasse with Sémillon.” Separating the Sauvignon Blanc from the Sauvignonasse turned out to be not so simple after all.

But in the 1990s, Chilean vintners began a serious effort to replant vineyards with true Sauvignon Blanc, and today any reputable winery that labels its wine as Sauvignon Blanc is indeed bottling wine made entirely (or almost entirely) from true Sauvignon Blanc. One Chilean Sauvignon Blanc particularly worth seeking out is made by Casa Lapostolle, a critically acclaimed 19-year-old winery founded by the owners of Grand Marnier.

I had the opportunity to sample a glass of the 2012 Lapostolle Casa Grand Selection Sauvignon Blanc over dinner with winemaker Andrea León Iriarte and Liz Barrett, Vice President of Corporate Communications for the wine’s U.S. distributor, Terlato Wines. It put to rest any remaining doubts as to whether Chile can make world-class Sauvignon Blanc.

The grapes for this wine come from the stony Las Kuras Vineyard in the Cachapoal Valley (south of Santiago), a former riverbed, and the vineyards are certified as both organic and biodynamic. Iriarte also noted that the grapes are harvested by hand at night. This practice helps preserve some freshness in the fruit as well as reduce energy costs. Because the grapes come in already cool from the night air, the winery expends less energy bringing the grapes to the correct temperature for fermentation.

The aroma was very reassuring, the rich lime and chalk notes already indicating a wine of fine balance. Iriarte and Lapostolle sought a round Sauvignon Blanc, in contrast to the sharp wines this variety sometimes produces. They succeeded — this Sauvignon Blanc had creamy fruit and focused, limey acids kept well in check. After a lift of white-pepper spice, the stone in the vineyards became apparent in the long finish. Complex and delicious.

What leaves me practically cross-eyed with disbelief is that this wine, which exhibits no small amount of finesse, can be had for less than $10 at Binny’s. It could stand toe-to-toe with Sancerres which cost more than twice as much. I can’t think of a better Sauvignon Blanc value to be had anywhere.

This wine, it should be noted, isn’t 100% Sauvignon Blanc. The 8% Sémillon and 2% Sauvignon Gris surely help round out the edges. Iriarte confided that there likely is just a touch of Sauvignonasse in the blend as well, from “just one or two” old vines that weren’t removed from the vineyards. “It adds to the complexity,” she said. It’s also a subtle nod to Chilean wine history; a faint whisper from another era.