The trick is to grate the fresh root directly into lemon or vinegar so that it gets as little exposure to air as possible. If all this sounds like too much work, you can buy the root already dried as wasabi powder. This is the amazingly hot paste served with some Japanese dishes. Reconstitute the powder a half hour before serving by soaking 1 tablespoon of powder in 2 tablespoons of water. Keep reconstituted wasabi in the refrigerator.
Black pepper has the distinction of being an important spice all over the world.
Once literally worth its weight in gold, the humble peppercorn has played an important role over the ages. The trade routes from India to ancient Rome were established mainly because of this spice, and its trade made Venice, Genoa, Amsterdam and Bruges, Belgium, wealthy cities. Today, the United States imports more pepper than any other country. I have heard many people claim that black pepper is not healthy. I am not sure how pepper fell into disfavor, but perhaps it was guilt by association.