Wasabi is a root vegetable grown in the mountain areas with very shallow running cold water and it has to be in area that is not muddy, like a very sandy area. It is very hard to grow wasabi. That is why real wasabi root is very expensive. Once you have it and you taste it, it is so much better than other wasabi, fake wasabi, such as tube wasabi or powder wasabi. Those are like horseradish or mustard, whatever they put together with it and then put the coloring in it, that is fake wasabi.
This is fresh wasabi root. This is very short but sometimes comes like this and sometimes bigger, a little thicker. These are the stems and the little leaves. Of course, we eat the root and also the stems. The stems you can cut in little pieces, you can marinate them in soy sauce or any other thing and it is very fragrant, a little bit spicy and very good.
The root you just peel off a very thin layer outside of the skin. This is the wasabi grater. The surface is made of shark skin so you just grate it, grate it. Like a massage motion, nice and creamy, bright green colors and the aroma comes out and tastes so much better. It is very spicy but at the same time it is very sweet. You can taste the sweetness of the root and then very spicy. If you have the chance to have real wasabi root, try it and you will really enjoy it.
The way you eat sushi with wasabi; I usually do not eat wasabi at all. I only put a little bit on the top of the fish and eat it but not all fish, just the fatty types of fish like yellowtail or toro, which is a fatty tuna. But if you like a little wasabi you can use it but not too much. Certainly you do not want to take a whole block of wasabi and put it in the soy sauce and then mix and mix and mix it, and then you are dipping into, or swimming into the soy sauce/wasabi mixture and eat it... You are like, 'Ugh!' That is not the way to eat sushi.
Sushi is very delicate so do not forget, you are not trying to taste the wasabi and the soy sauce; you are trying to taste the fish and the delicate flavor of the sushi rice.