Place a sheet of nori, shiny side down, in the palm of your hand. Add about 1/4 cup rice along a short side of the nori. Flatten rice with your fingertips, to cover about 1 inch of the nori. Spread with desired amount of wasabi. Top with choice of vegetables and fish. Roll into a cone shape to enclose. Serve immediately with soy sauce and pickled ginger on the side.