My friend Vaughn Davis, who came by his taste for wasabi honestly ― from his Japanese mother ― was recently surprised to find this potent green horseradish on a restaurant menu, mixing it up with mashed potatoes. The wasabi potatoes were served with roast chicken. Intrigued by this defection from tradition, he tried an even bolder version, enhancing wasabi's green presence with parsley. He serves his potatoes with salmon. Use refrigerated wasabi paste in tubes or canned wasabi powder.