Wasabi is difficult to grow outside of its natural Asian environment of mountain streams sheltered by overhanging trees and foliage. Hence it is rare and expensive. Powder or tubes of paste commonly labelled as wasabi often contain either none or just minor traces of the real thing.
So when you get a rhizome it is worth looking after. Wrapped in moist paper can be kept in the chiller section of your fridge for approximately a month.
How to prepare wasabi - (be happy)
Firstly, thoroughly clean the top end (which has the most flavour) and gently break off any shoots (they can be finely chopped to make an interesting addition to a salad). Do not peel the skin of the wasabi stems because the most intense flavour is the outer part that is closest to the skin. Next, the wasabi is best prepared using an "Oroshi” which, rather than grating into lumps, pulverises the wasabi into a paste. The Oroshi pictured here is a traditional wooden paddle shape covered with sharkskin to form the abrasive surface against which the wasabi is gently rubbed in a continuous circular action. This results in a fine wasabi paste. Small round ceramic alternatives to the traditional "Oroshi" are widely available.
A commonly held belief in Japan is that one should be in our happy light-hearted frame of mind while rubbing wasabi which results in a fine paste that releases more of the uniquely pungent wasabi flavour. Rubbing aggressively creates lumpy paste which does not taste as good as a smoother emulsion. Science supports this, as it is the release of wasabi's glucosinolates and the enzyme myrosianse that create isothiocynates, which result in the most desirable flavours and creates the best nutritional advantage. So once more we find that traditional beliefs can be ratified by the evidence of scientific research. Maybe we should all listen to grandmother more often!
The process of preparing wasabi is often referred to as grating but using a traditional grater simply carves off lumps that will not achieve the stimulating flavours of wasabi.
As we have written about previously timing is important: it is best to prepare your fresh wasabi during the late stages of food preparation so that ideally it is served within ten minutes of being created. This link below explains why:
"This church had 134 years of weddings, blessings and Sunday school; it must be Inculcated with love, the walls must exude happiness and joy." Keiko Yamaga-White November 2007