Despite what you may have heard or read, the familiar green paste of wasabi is not
made from the ‘root’ or ‘rhizome’ of the plant at all, but the stems. The stems are
short, thick and quite knobbly in appearance and grow from ground level upwards so
they are in fact a stem, not a root or rhizome of the plant.
Begin by grating the stem in a circular motion on the grater to produce a fine, soft
paste. The paste should then be moulded into a loose ball and allowed to rest for
at least 2-3 minutes to develop its characteristic intense heat and sweet flavour.
After the resting period the wasabi is usually served either direct with the meal
or presented in a series of small bowls with other condiments such as soy sauce,
mirin and pickled ginger.
Fresh wasabi loses its intense flavour within a few hours as the flavour components
are quite volatile and will evaporate off, so for this reason wasabi should always
be grated fresh for each meal.
All of the wasabi stem can be grated into paste, however the bottom of the stem is
the oldest material and is usually hotter whilst the top of the stem is younger material
and is a little sweeter and greener in colour. Many chefs grate a little from both
ends to ensure a uniform flavour and colour.
Storing Fresh Wasabi
Unused portions of wasabi stems can be stored for up to three weeks in a refrigerator.
Simply wrap in paper towel and seal in a snap-lock bag or airtight container and
then place in the vegetable compartment of a refrigerator. Change the wrapping every
few days. The cut surfaces will oxidise and darken but these can simply be peeled
off to reveal fresh wasabi ready to use.
Wasabi leaves and leaf stalks keep really well if treated similarly to lettuce and
other leafy vegetables. Keep them damp and store in the vegetable compartment of
Wasabi flower stems are best stood upright in a container of water and kept cool,
so the remaining buds can open up ready for use.