Although most of us are familiar with horseradish in its prepared form - in jars or bottles - the fresh root is a rarer thing.
Commercial horseradish is usually mixed with ingredients such as vinegar and oil, but the strong, fiery taste we are familiar with manages to fight its way through. The fresh root is different, at least initially. Although it seems it should be stronger because the flavours are not diluted, it's actually milder.
At first the freshly sliced root tastes sweet, which slowly gives way to the hot, bitter flavour - but it's not eye-watering and sinus-clearing like some of the commercial preparations. The sweetness dissipates quickly though, and if fresh horseradish is sliced (or grated) too far in advance of being consumed, you'll taste only the fiery qualities. Japanese wasabi powder or paste is usually made from tinted horseradish rather than fresh wasabi root (which is very expensive).
Bought horseradish root should be quite firm. Wrapped in cling-film and stored in the fridge, the root keeps for weeks.
Horseradish is frequently paired with strong meats, especially beef. The easiest way to make it would be to grate it (preferably with a rasp grater with super-sharp teeth) and mix with sour cream. Make it as close as possible to serving time.
I also like it in a salad. Julienne roasted beets and fresh apples, then mix with grated fresh horseradish, sour cream and fresh dill.