Cook rice according to package directions. Spread in 13 x 9-in. (3 L) baking dish to cool. Meanwhile, in microwaveable bowl, stir rice vinegar with sugar and salt. Heat 30 sec. to 1 min. or until steaming. Stir until sugar and salt are dissolved. Toss rice with mixture; cool completely.
Place sesame seeds in shallow dish. Using wet hands, divide rice into 12 portions and roll into balls. Flatten each rice ball. Place an oyster in the centre. Seal oyster in rice and re-shape into ball. Roll in sesame seeds to coat. Repeat for 12 balls. Set aside.
Mix mayonnaise, chives, lemon zest and lemon juice.
Serve rice balls topped with mayonnaise mixture and nori strips.
Serve with wasabi and pickled ginger.