In a large bowl combine garlic powder, onion powder, sweet paprika, salt, pepper, cornflour and egg. Add the chicken and toss until all the pieces are covered well with this pasty mixture and set aside whilst preparing the sauce.
In a medium size bowl, whisk together all the sauce ingredients and set aside.
In a large frypan, heat oil to medium-high heat and add coated chicken pieces. Cook the chicken for 3-4 minutes on one side then turn and a further 2 minutes on the other side til nice and golden all over. Remove and drain on a plate with paper towel.
In a clean frypan, over medium heat, add the sauce and stir for 2-3 minutes til it bubbles gently and begins to thicken. Turn the heat off and return the cooked chicken bites back to the pan. Stir gently so that the sauce evenly coats each piece chicken.
If desired, serve on a bed of rice and garnish with sliced spring onions and sesame seeds.