Cook the rice according to instructions on the packet.
Meanwhile, put the vinegar and sugar in a small saucepan and heat gently, stirring, until the sugar has dissolved. Turn off the heat and add the chopped pickled ginger and wasabi. Leave to cool. Cut the cucumber in half lengthways and scoop out the seeds with a teaspoon. Slice the flesh finely and add to the cooled vinegar mix.
When the rice is cooked transfer it to a dish, strain the vinegar mixture over it, reserving the cucumber, stir and leave to cool.
Transfer the cooled rice to a large salad bowl and combine gently with the cucumber, salmon, avocado and spring onions. Top with toasted sesame seeds and serve.