The botrytized (aszu) berries and bunches are harvested separately (aszu berries are hand-picked berry by berry, this is why it's a very slow and very labour intensive process) and crushed into a sort of aszu-paste. The uncrushed aszu berries or the mashy paste is then added to either new-wine or to fermenting must, and left to macerate. Macerating the aszu-berries or the aszu paste is a key step in aszu-making, as it helps extract a complex array of distinctive flavours. The wine is then matured for a minimum of three years in cask and bottle in the underground labyrinth of cellars before release.

Aszu classification was traditionally based on how many dry berries, aszu berries were added to a barrel of dry wine, made of non-aszu berries. Aszu grapes were historically hand-picked from bunches into 20 litre wooden tubs called puttony. Now it is based on sugar levels. The higher the number of puttonyos, the sweeter, the richer, and, of course the more expensive the wine is. Number of puttony is printed on the label.

Essence, which often takes long years to ferment to an incredible 3-5% alcohol, being the rarest wine of all.

Grams sugar per litre:

• 3 Puttonyos Aszu: 60 - 90 g/l
• 4 Puttonyos Aszu: 90 – 120 g/l
• 5 Puttonyos Aszu: 120 - 150 g/l
• 6 Puttonyos Aszu: 150 - 180 g/l
• Aszu Essence: 180 - 450 g/l
• Essence: 450 - 850 g/l