Mix the rice vinegar with two teaspoons of sugar and a dash of salt. Stir thoroughly and set aside.
Put the rice in a colander and wash thoroughly under cold running water. Leave to drain for 30 minutes. Place in a saucepan with the water and bring to the boil, while stirring, then reduce to a low simmer. Cover and cook without stirring for 10 minutes. Remove from the heat and set aside for a further 10 minutes. Transfer to a non-metal bowl and add the rice vinegar seasoning. Cut the seasoning through the rice with a wooden spoon, for about two minutes. Set the rice aside and allow to cool to room temperature.
Pick through the crab to remove any shell or cartilage. Cut the avocado in half, remove the stone and thinly slice the flesh. When sliced, squeeze on some lime juice to prevent the avocado from dis-colouring.
Cut the nori sheet in half. Place, rough side up on a rolling mat with the long edge towards you. Cover with one portion of sushi rice spread in a thin layer. Leave about 2cm of bare nori at the far edge. Sprinkle on some sesame seeds and press gently to make sure the seeds are stuck to the rice.
Turn the nori and rice over so as the rice covered side is against the sushi mat and the bare nori strip is closest to you. Place some crab, avocado and a smear of wasabi on the bare nori strip. Lift the near edge of the mat and roll the sushi away from you, pressing in the filling as you go. A little water may be needed to seal the far edge.
Repeat the process to make 6 rolls. Slice each roll into even pieces using a clean wet knife.
«A cheaper alternative to fresh crab are crab sticks which can be used in this recipe. They are found in all supermarkets.»