• In a small saucepan, combine vinegar and sugar. Bring to a boil, and stir until the sugar has dissolved, about 3 minutes. Remove from heat, and set aside. In a small saucepan, bring the rice, salt, and 1 cup water to a boil. Reduce heat to a simmer, cover pot, and cook until rice is almost tender, about 15 minutes. Remove from heat, and stir in the reserved vinegar mixture. Cover the rice with a damp towel, and set aside to cool.

  • In a small bowl, combine the mayonnaise and wasabi; set aside.

  • Slice each shrimp in half crosswise, and cover pieces with a damp towel, or refrigerate until ready to use. Place sesame seeds in a small bowl. Cut nori into 24 1 3/4-inch triangles. Fill another small bowl with water, and set it on your work surface. Dampening your hands frequently with the water, roll the cooled rice mixture into 1 1/4-inch balls. Dip the bottom of each rice ball into the sesame seeds, and set it on a nori triangle. Top with a small dab of wasabi mayonnaise, just enough to adhere the shrimp to the rice mixture. Place 1 shrimp half, cut side down, on each rice ball, and top with 1/4 teaspoon of salmon roe. Serve with soy sauce, if desired.