Cover a bamboo sushi rolling mat with plastic wrap.
Place a sheet of nori on the mat.
Dip hands in water and clap to remove excess water. It helps to keep small bowl of water near you and a towel.
Spread a layer of rice across the nori. You will use about 1 cup cooked rice per full nori sheet.
Spread rice over whole surface of nori (no gap). Lay slices of salmon evenly over half.
Flip nori over (rice/salmon side down, nori up).
Place 2 tbsp crab mix, 2 slices avocado and 3-4 thin cucumber strips lengthwise in a strip across the rice. Placement should be about 1 inch or so from the bottom of the rice paper. Be careful not to put too many or sushi roll will not close well.
Use bamboo mat to lift edges up and over filling. Use fingers to tuck roll.
Tuck mat tightly into roll shape so only nori with no rice is exposed, pull back and tighten.
Move mat and shape roll, repeat squeeze and shape.
Slice and wipe with wet towel after each slice to prevent knife from getting too sticky.
Cut in half and then each half into 3 segments.