The vast majority of all the wasabi served in the world is made of horseradish, Chinese mustard, and food coloring. The real thing is quite rare, as wasabi is the world's most expensive crop to cultivate. Edwin's Lee's short film Wasabia Japonica follows Shigeo Iida as shows us his 8th-generation wasabi farm, one of the few in the world to grow authentic organic wasabi. Read more about the short film at the Atlantic. -via Metafilter
You're right about opening up the sinuses, Collin - that stuff is called "Japanese Dristan" for a good reason.