Buried in the ground. Coated in beeswax. Sealed with a stone or wooden cap. A qvevri (also written kvevri) is a large egg-shaped clay vessel that has been used to ferment and age Georgian wine for thousands of years.
The method is simple and strange. Grapes are pressed. The juice, skins, seeds, and stems all go in together. The vessel is sealed and left underground, where the earth acts as a natural temperature regulator. Six months later: wine.
The result is something you cannot replicate any other way. The grape solids impart tannin, texture, and a deep golden-amber color that is nothing like the whites you have tried before.