Ice wine is best served chilled, but not as cold as it is when you harvest the grapes from which it is made.

That’s because winemakers leave the grapes on the vine into the late fall or winter until the shriveled, almost raisins freeze solid, and then they pick them. And in the wine country along Lake Erie, they round up volunteers to help pick them by hand and in the dark (so the grapes don’t thaw in the sun), a harvest in which I got to participate one January morning several years ago for a story in the Post-Gazette.

I thawed out while watching the juice be mechanically pressed from the frozen grapes, which, because some of the water is discarded as ice crystals, is concentrated with not only sugar but also acids and other flavors. A long and incomplete fermentation results in sweet, almost syrupy ice wine, which was first made commercially in Pennsylvania in 1984 by Mazza Vineyards. Kathie Mazza described it for me as “liquid dessert.” For winemakers, especially in Ontario and elsewhere in Canada where they write it “icewine,” it’s become liquid gold.

This year, the consortium that includes Mazza and two dozen other Pennsylvania and New York wineries (it now calls itself Lake Erie Wine Country) is promoting ice wine with its first Winter Celebration of Ice and Specialty Wines, appropriately titled “Frozen.”