1 rectangle of packaged roasted seaweed
3/4 cup cooked rice for sushi (<a href="http://cooking.nytimes.com/recipes/10352-craig-claibornes-sushi-rice">see recipe</a>)
1 teaspoon sesame seeds
2 1/2-inch-thick strips of peeled, pitted avocado
2 crab-flavored fish cakes (see note)
2 tablespoons red lumpfish roe or smelt roe
Japanese horseradish (see recipe) for garnish
Pickled ginger for garnish