Horseradish is the main ingredient in imported wasabi. Guess where Japanese manufacturers get their horseradish. Guess, I said. America. That's right, America.
They also sell real wasabi, a type of horseradish, both plants in mustard family. Whereas wasabi is more persnickety growing near rivulets, and so more expensive, horseradish is rampant and very easy to grow. It will take over the side of your house.
The bowl below is diluted with water.