Combine the flour, cornstarch, and salt in a shallow dish; in another bowl, whisk in eggs.
Take each piece of the chicken and dip it into the egg mixture, then transfer it to the flour mixture.
Repeat until you have all the pieces of the chicken well covered with the flour mixture.
In a wok or a large saucepan, add the oil over medium-high heat; once hot, add the chicken and cook until the chicken is all cooked and no longer pink on the inside.
Remove the chicken from the wok and reserve.
In the same wok, add all the sauce ingredients and mix to combine everything. Cook until the sauce has thickened.
Reduce heat and add the chicken back to the wok with the sauce.
Continue cooking and stir until the chicken is well covered with the sauce.
Turn off the heat and sprinkle with green onion and sesame seeds