[Japanese Horseradish; Wasabia japonica]
This very pungent green fleshed root is used grated as a condiment, particularly to accompany sushi. Most sushi lovers, however, have never tasted wasabi. Pretty much all sushi bars in the US and nearly all in Japan serve a fake wasabi made from Horseradish, mustard seeds and green food coloring. Real wasabi (hon-wasabi) has a more refined hotness, a sweet after-taste and is not nearly so bright a green as the fake. It's also very expensive and the flavor is extremely perishable.
Imported "wasabi" purchased as tiny cans of dried powder or tubes of paste is all faked up from horseradish. The Japanese can export horseradish under the name "wasabi" because the Japanese name for horseradish is "seiyo wasabi" (Western wasabi). They can even call it "real wasabi".
Several companies set up wasabi production in North America. At first they expected to export it to Japan, but local demand has been so great there's little left to export. Two grades are grown in North America: sawa-wasabi (semi aquatic - for culinary use) and oka-wasabi (field grown - for the nutritional supplement industry). Fresh product is available from these growers (see below for suppliers). Photo "borrowed" from Pacific Coast Wasabi.
More on Cabbage Roots.
Fresh Wasabi Rhizomes: These are a phone or Internet purchase direct from the grower - expect to pay for 2nd day air or better and US $100 to $150/pound. Pacific Farms has stopped selling rhizomes but they are still available from Real Wasabi and Pacific Coast Wasabi. Wrapped in damp paper toweling inside a bag these can be kept refrigerated for up to 30 days, otherwise, freeze.
To prepare, grate on a very fine grater. Traditionally this is a piece of shark skin but a very fine ceramic or stainless grater will work. Quickly gather the grated paste into a ball and cover tightly with plastic wrap. Let sit that way for about 8 minutes to develop flavor, then serve immediately. After 20 minutes the flavor will start to rapidly decline. It can be restored to some extent by remixing and rewrapping. Some say a pinch of sugar will help.
Wasabi Paste: This is primarily available from Pacific Farms. It looses its strength rapidly at room temperature so it is shipped frozen - again 2nd day air or better. It must be kept frozen until needed, then refrigerated. There have been complaints that this wasabi is difficult to squeeze out of the tube, but you can always cut off the bottom of the tube and squeeze it out that way. So-called "Wasabi paste" imported from Japan is a chemical stew based on horseradish - but it squeezes easily.
Dried Wasabi: This form is problematic because normal drying pretty much destroys the flavor. Freeze drying works much better, but the product is still very perishable. It will last a year refrigerated in a tightly sealed container away from light. Real Wasabi seems to be the main supplier of this form. That imported from Japan is all fake, made of horseradish, mustard and dye. Preparation is easy - just mix equal volume of powder and water into a paste and let sit 10 minutes to develop flavor. Again, it should not be prepared until just before use.Suppliers: