In a large bowl, mixed together the marinade ingredient. Set aside.
Place the sliced chicken breast in another bowl in a zip lock or a bowl. Spoon in 2/3 cup of the marinade and mix it with the chicken breast. Marinate the chicken for 30 minutes.
When the chicken is ready, drain the marinade and prepare a large baking sheet and spray it with non stick oil. Set aside.
Scramble the egg in a bowl. Pour in one cup of corn starch on a flat plate. Keep the cornstarch handy as you may need more of it later.
Pre heat oven at 400 F.
Dip the chicken breast into the scrambled egg and roll it into the cornstarch. Place it on the baking sheet. Do the same to the rest of the chicken.Bake the chicken for 10 minutes then turn the other side for another 10 minutes.
When the chicken is almost ready, place the remaining of the marinade into a sauce pan and let it simmer. Mix the 1 tablespoon cornstarch with 2 tablespoon of water and mix until smooth. Then pour mixture into the simmering marinade. Continue mixing until the marinade is sticky.
When the chicken is cooked, put them into a deep bowl and drizzle in the marinade or toss the chicken gently. Garnish with onion leaves and lemon zest. NOTE: For me, I I drizzle the chicken with the sauce so that the breading is still intact.
Serve Hot.