Makes 4 rolls (32 pieces) In a small bowl combine wasabi and mayonnaise. Place one long side of one nori sheet lengthwise on bamboo mat abouyt 3 slats from the edge closest to you, shiny side down. Dip both hands in finger bowl, shaking off excess. Working from one side to the other, spread one quarter of rice evenly over nori leaving a 1-inch (2.5 cm) strip uncovered on the long side farthest from you. Gently rake fingers across grains to spread rice evenly. Build a small mound of rice along edge nearest the uncovered nori strip to help keep fillings in place. Spread wasabi mayonnaise across rice then layer fillings, making sure each extends completely to both ends so there will be filling in the end pieces when cut. Using your index finger and thumb, pick up edge of bamboo mat nearest you. Place remaining fingers over fillings to hold them as you roll mat forward tightly, wrapping rice and nori around fillings. The strip of nori without rice should still be visible. Press gently and continue rolling forward to complete roll. Gently press mat to shape and seal roll. Unroll mat and place roll on cutting board with seam on bottom. Wipe a sharp knife with a damp cloth and cut roll in half. Pick up one half roll and turn it 180 degrees so cut ends are on the same side. Cut rolls in half, then in half again to make 8 pieces, wiping knife between cuts. Repeat for remaining rolls. Serve with remaining wasabi and soy sauce.