I found that this sauce is from Thailand, Japan, Korea and Hawaii. Not sure which is correct and it may be from all of these places and more, with a variation here or there. It is simple and delicious, sweet with a tang and sticky.
I did not have any panko crumbs as all the recipes I saw called for so I mixed 4 TBSP of flour and 4 TBSP of white corn meal together and dredged my chicken in it. The chicken I cooked in a very small amount of oil so as not to saturate the chicken but give it a crispy coating.
For the sauce you take:
1/3 cup ketchup
1/4 cup soy sauce
1/4 cup sugar
2 tsp Worcestershire sauce
1/4 tsp fresh cracked pepper
Stir these ingredients well in a small sauce pan and simmer while the chicken is cooking. It will thicken up and make a lovely dark burgundy sticky sauce.
I served this with rice and a simple salad. VERY good and I will definitely be doing this again.
I am not sure where I got the recipe as I was surfing around and found many variations. I did see that most added hot sauce or red pepper flake to the sauce.