When most of us are consuming wasabi, we are actually eating a blend of horseradish, sometimes with mustard. Pure wasabi is rare because the wasabi plants can be finnicky, requires a close eye while growing, and reaches maturity slowly after almost three years. Because wasabi production is so time consuming, it makes sense to create the effect with blends.
Pure wasabi powder has a more complex flavor than the blends. Initially, it has a sweet, green aroma. When turned into a paste, the wasabi has a sharp and sudden heat but then cools into a nutty flavor. Rather than just heat (and pain), pure wasabi has subtle notes that are missing from horseradish.
To use the wasabi, mix the two times the powder as to water (2:1) in a bowl. Turn the bowl upside down on to a plate, trapping the gas and creating a fuller flavor. Wait ten minutes before uncovering.
Pure wasabi tends to lose its full flavor the longer it sits, so only make right consuming or at least within 15 minutes.
Pure wasabi powder is sold in 5 gram glass bottles.