As you place the rice onto the nori sheet, fashion it into a long column that makes a long strip right across the middle of the sheet. Gently press it toward the edges, so the whole sheet is covered with a thin blanket of rice, maybe just a grain or two thick. Keep your fingers wet if necessary, but try to use as little water as possible to avoid dampening the rice.
TIP: Many people encase their bamboo mats in plastic wrap. This makes it both easier to work with and easier to clean.
IT'S FILLING TIME
If you're using wasabi, take a tiny dab of it on your finger and make an almost transparent green strip across the rice. Across the middle of the sheet, lay out the asparagus spear and enough carrot slivers to run the length of the roll.To roll, gently take edge of mat in both hands, leaving it on the board or counter surface. Roll mat and sheet together about one third of the way. Gently apply pressure, and try to keep the roll rounded rather than flat.
Unroll slightly and repeat twice more, also at one-third intervals. By the end, the mat should have a substantial lip overlaying the roll, and that lip can be tucked under the roll so that the almost-finished product is completely wrapped in bamboo. Now you can fine tune the roll with pressure to make sure it is perfectly rounded.
Remove mat and use your sharpest knife to cut the rolls into six or eight pieces, depending on how thick you want them. (Probably NOT a step for the kids). To make sure the pieces are all even, first cut roll in half, and then cut each half evenly into two or three more pieces.
Repeat with remaining sheets, rice and fillings until finished. Arrange on plate or platter, and serve with shallow bowls of light soy sauce. The rolls are traditionally served with gari, or pickled ginger (available in the same stores), which people eat in between bites to "cleanse" the palate, and with wasabi, which can be dabbed onto the rolls to add a little spice.
