In a small bowl, whisk cornstarch with soy sauce, vinegar, hoisin sauce, ginger, garlic powder and pepper. Set aside.
In a large bowl, combine egg, evaporated milk, bread crumbs, onion salt, garlic powder and black pepper. Crumble beef over mixture and blend well. Shape into 1-inch balls.
Tear off 4 12-inch pieces of Reynold's Wrap. Set 1/4 of the vegetables onto center of each piece of foil. Top each with 1/4 of the meatballs and 1/4 of the sauce. Fold foil over mixture and crimp edges to make packets. Place packets on a cookie sheet.
Bake at 350 degrees F. for 30 minutes, or until meatballs are fully cooked.
To serve, place 1/2 cup rice on each of 4 serving plates. Open each packet over rice. Sprinkle with sesame seeds.