Start by putting the rice on to boil so it is ready for serving as soon as the meatballs are cooked. Follow the package instructions for cooking directions.
Using your hands, combine the minced beef with the panko breadcrumbs, egg, ginger, garlic, soya sauce and sriracha sauce.
Form the minced beef mixture into meatballs about the size of golf balls.
To help firm up the meatballs, put them on a plate, cover and place in the refrigerator until needed.
In the meantime, heat a small saucepan to a medium-high heat, add all the teriyaki sauce ingredients except for the cornflour and bring to the boil.
Mix the cornflour with a 1/4 cup of water, stir the mixture into the sauce and simmer for 5 to 10 minutes or until thickened.
Finish the teriyaki sauce by removing the onion and ginger slices and season with freshly ground black pepper. Set aside.
Heat a large frying pan on a medium-high heat, pour a few tablespoons of sesame seed oil in the pan and fry the meatballs for approximately 8 to 10 minutes or until they are golden brown all over.
Spoon over 1/3 of the teriyaki sauce into the pan with the meatballs and coat them in the sauce.
Serve the juicy teriyaki meatballs over the rice, garnish with spring onions and sesame seeds and spoon the remaining teriyaki sauce over the top.