Place rice in a large colander and rinse with cold water until water runs clear. 

Meanwhile, in a small saucepan heat 3 tablespoons vinegar to a simmer. 

Remove from heat and whisk in sugar and salt until dissolved. 

Place vinegar mixture and rice in a large bowl and toss to combine. 

Let cool completely.

In a medium bowl, toss cucumber, avocado, carrot and crabmeat until combined.

Divide rice evenly between four serving bowls and top with cucumber mixture.

 In a small bowl, whisk together remaining 2 tablespoons rice vinegar and soy sauce. 

Drizzle over the top and garnish with pickled ginger and sesame seeds.