1. To prepare rice for this or any other sushi dish, rice must be pickled.
2. Combine vinegar and sugar in a enamel saucepan and bring to a boil.
3. Cook, stirring until sugar is completely dissolved. Remove from heat.
4. Stir 2 tablespoons of vinegar - sugar mixture into the cooked, still warm, rice.
5. Warm rice absorbs the mixture more completely.
6. Stir sesame seeds into rice.
7. Press pickled rice into a square on a small serving platter.
8. Cut rice into squares, and leave rice squares in place.
9. Press each square lightly so that rice clings, and place a small dab of Wasabi paste on each.
10. Press a bit of crabmeat, fish roe, and avocado on each square.