Whisk together rice wine vinegar through soy sauce in a small bowl. Set aside.
Scrub oysters with a stiff brush under running water. Insert an oyster knife into the hinged edge of each oyster; twist knife handle back and forth until top shell is loose. Slide oyster knife along the bottom of the top shell to detach muscle. Remove and discard top shell, keeping the oyster in the deeper bottom shell.
Spoon about 1 teaspoon sauce over each oyster.
Grill, without grill lid, over high heat (400° to 500°) 1 to 2 minutes or until sauce boils. Remove oysters from grill with tongs, being careful not to spill sauce. Serve immediately.