Adjust the oven rack to middle position and preheat oven to 425 degrees.
In a medium-sized bowl, combine the sauce ingredients and whisk together. Set aside.
Wash green onions. Cut and finely dice the white portion for the meatballs. Thinly slice the green portion and set aside for garnish.
In a second bowl, combine beef, panko, ginger, green onion whites, soy sauce, salt and pepper.
For into 20- 11/2 inch meatballs.
Cook meatballs in preheated oven for 14-16 minutes or more.
Remove from oven when done and toss with meatball sauce and serve over rice. Garnish with green onions, toasted sesame seeds and chili flakes to taste.