[hn_throwaway_99]

Can you explain? I don't understand, as mustard is made from the mustard plant, not grapes.

[sam_lowry_]

Mustard grains are soaked in wine vinegar nowadays.

Before phylloxera, a grape that gives a wine with high acidity was used.

It went extinct.

[sam_lowry_]

correction: mustard flour, not grains.

[coryrc]

Dijon