Although it is not common and not recommended, yes, you can freeze wasabi. Wasabi paste is easier to handle. Simply put a pack of wasabi paste in a container and let it freeze. When it comes to fresh wasabi, the best practice is to freshly grate the root before serving. But, if you have to, consider freezing grated wasabi instead of a whole root. Try to consume it not too long after being frozen. To thaw frozen wasabi, do it safely in the refrigerator.