Wasabi is a Japanese horseradish root that is powdered and then has a green dye added to it. I recommend you make your wasabi from wasabi powder. (The wasabi paste that comes in a tube loses much of its heat and seems really expensive.) Make sure the can bag of wasabi powder has not been refrigerated. We have found that if you leave the powder open to the air, it looses some of its heat over time.
We have heard of one person in Oregon who has been able to grow the Japanese horseradish root and sell the powdered product. The Japanese horseradish root grows in cold, fast running, mountain streams. Powders with 4 different degrees of hotness are offered. The prices make your pocketbook ache oh some cheap.
We serve our wasabi sauce thinned so you can better control how much wasabi goes onto each oyster.