Riesling Trockenbeerenauslese

Trockenbeerenauslese sits at the top of the German Prädikat system, and it is among the most laborious wines in the world to produce. The name translates literally as dry berry selected harvest, and it describes exactly what happens: individual berries, shrivelled by noble rot to something resembling a raisin, are picked one at a time by hand.

The rot in question is Botrytis cinerea, which in damp autumn mornings followed by dry sunny afternoons punctures the grape skin and allows water to evaporate. Sugar, acid and flavour concentrate enormously; the fungus also contributes its own aromatic signature of honey, saffron and dried fruit. In the wrong conditions the same fungus is grey rot and ruins the crop, which is why the wine cannot be made every year.

The yields are minute. A picker might spend a day gathering enough fruit for a few bottles, and the juice is so viscous and sugar-laden that fermentation struggles to begin and stops early, often below eight per cent alcohol.

What results is extraordinary: deep gold to amber, syrupy in texture, with apricot, honey, marmalade, dried pineapple and beeswax, and — critically — the piercing acidity that Riesling retains no matter how ripe it gets. That acid is what keeps the wine from being cloying and what allows it to age for fifty years or more, slowly turning from fruit towards petrol, caramel and dried herbs.

It is made in tiny quantities in the Mosel, Rheingau, Nahe and Pfalz, sold in half-bottles, and priced accordingly.