Stir together ground meat, egg, cilantro, scallions, sesame oil and salt with a fork until just blended.
Spread cornstarch in a shallow baking pan. With wet hands, form meat mixture into balls.
Put meatballs into baking pan as they are formed. Roll in cornstarch (balls will be soft).
Heat vegetable oil in a 12’ heavy skillet over medium heat until hot but not smoking. Cook half of each meatball, then roll over and cook other side until done. Transfer to paper towels to drain.
Blend rice vinegar and soy sauce and serve as a dipping sauce. Makes 30 balls.