Place avocado half on cutting board and slice it horizontally in half.
Cut each slice into equal strips, lengthwise, about 1/2-inch thick.
Prepare crab filling: Cut each crab stick in half, lengthwise.
Place bamboo rolling mat (sudare) on cutting board. Make sure that bamboo mat and cutting board are dry. Lay one sheet of nori shiny side down onto bamboo mat.
Place about 1 cup of prepared rice on nori sheet and spread it out gently with spatula (shamoji), covering the entire nori sheet, except for 1/2 inch at the far end. Don't push rice down into nori sheet, just spread gently. You may as well dip your hands in cold water and use them for spreading rice (instead of spatula). Whichever is more comfortable for you.
Place several crab strips at the end closest to you.
Add several avocado strips.
Wet slightly the exposed strip of nori sheet (at the far end, not covered with rice) with cold water, using your fingers or brush. Lift the front of bamboo mat closest to you. Roll by pressing bamboo mat firmly on the nori sheet. Make sure to release bamboo mat as you make the roll. The nori will stick to itself when roll is complete.
Let the roll rest for a minute. Moisten sharp knife with cold water and cut the roll into 5 to 6 pieces.